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Influence of Squatting Depth on Jumping Performance
Abstract
It is unclear if increases in one repetition maximum (1-RM) in quarter squats result in higher gains compared to full depth squats in isometric force production and vertical jump performance. The aim of the research projects was to compare the effects of different squat variants on the development of 1-RM and their transfer effects to Countermovement (CMJ) and Squat Jump (SJ) height, maximal voluntary contraction (MVC) and maximal rate of force development (MRFD). Twenty-three women and 36 men (mean age: 24.11±2.88) were parallelized into three groups based on their CMJ height: deep front squats (FSQ, n=20), deep back squats (BSQ, n=20) and quarter back squats (BSQ¼, n=19). In addition a control group (C, n=16) existed (mean age: 24.38±0.50). Experimental groups trained 2 d·wk for 10 weeks following a strength-power periodization, which produced significant (p≤0.05) gains of the specific squat 1-RM. FSQ and BSQ attained significant (p≤0.05) elevations in SJ and CMJ without any interaction effects between both groups (p≥0.05). BSQ¼ and C did not reveal any significant changes of SJ and CMJ. FSQ and BSQ had significantly higher SJ scores over C (p≤0.05). BSQ did not feature any significant group difference to BSQ¼ (p=0.116) in SJ, whereas FSQ showed a trend towards higher SJ heights over BSQ¼ (p=0.052). FSQ and BSQ presented significantly (p≤0.05) higher CMJ heights over BSQ¼ and C. Post-test in MVC and MRFD demonstrated no significant changes for BSQ. Significant declines in MRFD for FSQ in the right leg (p≤0.05) without any interaction effects for MVC and MRFD between both FSQ and BSQ were found. Training of BSQ¼ resulted in significantly (p≤0.05) lower RFD and MVC values in contrast to FSQ and BSQ. Quarter squat training elicited significant (p≤0.05) transfer losses into the isometric maximal and explosive strength behavior. Our findings therefor contest the concept of superior angle specific transfer effects. Deep front and back squats guarantee performance-enhancing transfer effects of dynamic maximal strength to dynamic speed-strength capacity of hip and knee extensors compared to quarter squats.
... An important factor determining the gain in sprinting performance seems to be squat depth, which we classified in accordance with Hartmann et al., 35 meaning deep squat as 40°-45°, half squat as 80°-100°, and quarter squat as 110°-140°of knee extension. Studies have shown that deep barbell front and back squats yield superior results 35,37 while quarter und half squats simultaneously pose higher risks of injury. ...
... An important factor determining the gain in sprinting performance seems to be squat depth, which we classified in accordance with Hartmann et al., 35 meaning deep squat as 40°-45°, half squat as 80°-100°, and quarter squat as 110°-140°of knee extension. Studies have shown that deep barbell front and back squats yield superior results 35,37 while quarter und half squats simultaneously pose higher risks of injury. 35,[37][38][39] The transfer of high-load strength training to sports-specific motions is achieved through technique and plyometric training. ...
... Studies have shown that deep barbell front and back squats yield superior results 35,37 while quarter und half squats simultaneously pose higher risks of injury. 35,[37][38][39] The transfer of high-load strength training to sports-specific motions is achieved through technique and plyometric training. 17,[40][41][42] Therefore, it is recommended that both junior and senior soccer players make use of deep squats instead of half or quarter squats and combine these with sprint technique and plyometric training to maximize sprinting performance. ...
Practical Question: Is high-load squat training beneficial in improving sprinting performance in junior elite-level soccer players? Clinical Bottom Line: There is Level 3 evidence to support the validity of high-load squat training as a measure to improve sprinting performance in junior male elite-level soccer players. All three studies included showed significant increases in soccer-related sprinting performance.
... After the full-text screening, 16 studies were considered for qualitative analysis and meta-analyses. [53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68] Two authors provided missing data not published in the original studies. 54,60 ...
... In this regard, some studies found that each training group obtained the greatest 1RM improvements at the specific ROM at which they trained (eg, the partial squat group achieved more 1RM enhancements in the partial squat test than in the full squat test). 56,61,66,67 Conversely, other investigations showed that, although each training group maximized the strength gains at the specific ROM they trained, the full ROM group obtained the greatest neuromuscular improvements even in the partial tests. 59,63 It should be taken into account that the specificity principle could be related to the learning effect of participants, after regular practice. ...
... The use of exercise training makes it impossible to truly blind patients to treatment allocation; therefore, this was not considered in the overall risk-of-bias assessment of each study effect when interpreting the main results is the inclusion of complementary neuromuscular tests, not related to the specific resistance training performed during the intervention, for instance, maximal isometric contractions at specific angles. 56,64,67 Thus, taking into account these complementary evaluations, our results continue to support the greater efficacy of the full ROM training to enhance strength gains ( Table 2). ...
Background
Nowadays, there is a lack of consensus and high controversy about the most effective range of motion (ROM) to minimize the risk of injury and maximize the resistance training adaptations.
Objective
To conduct a systematic review and meta-analysis of the scientific evidence examining the effects of full and partial ROM resistance training interventions on neuromuscular, functional, and structural adaptations.
Methods
The original protocol (CRD42020160976) was prospectively registered in the PROSPERO database. Medline, Scopus, and Web of Science databases were searched to identify relevant articles from the earliest record up to and including August 2020. The RoB 2 and GRADE tools were used to judge the level of bias and quality of evidence. Meta-analyses were performed using robust variance estimation with small-sample corrections.
Results
Sixteen studies were finally included in the systematic review and meta-analyses. Full ROM training produced significantly greater adaptations than partial ROM on muscle strength (ES=0.56, P=0.004) and lower-limb hypertrophy (ES=0.88, P=0.027). Furthermore, although not statistically significant, changes in functional performance were maximized by the full ROM training (ES=0.44, P=0.186). Finally, no significant superiority of either ROM was found to produce changes in muscle thickness, pennation angle, and fascicle length (ES=0.28, P=0.226).
Conclusion
Full ROM resistance training is more effective than partial ROM to maximize muscle strength and lower-limb muscle hypertrophy. Likewise, functional performance appears to be favored by the use of full ROM exercises. On the other hand, there are no large differences between the full and partial ROM interventions to generate changes in muscle architecture.
... Two weeks before the study, all athletes were familiarized with the back squat, deadlift, countermovement jump (CMJ), and squat jump (SJ). As recommended previously (23), the familiarization involved 3 sets with 12 repetitions of the back squat and deadlift as well as 3 sets of 8 CMJ and SJ. The strength and conditioning coach chose weight and box height such that moderate effort from athletes, as well as high-quality technical execution was ensured. ...
... Maximal Strength Training. Workload was gradually increased during the 6-week training period, as recommended previously (23). Heavy back squat and deadlift exercises were performed as 3 sets of 6-8 repetitions in weeks 1-3 and as 4 sets of 2-4 repetitions in weeks 4-6. ...
... Sets were separated by a 5-minute rest period. For both the squats and deadlifts, barbell weight was chosen to assure muscular failure during the last 2 repetitions of the targeted repetition range, while maintaining high-quality lifting technique as recommended previously (23). Weight was increased for the next set by 2.5 kg if the athletes reached the upper limit of the targeted repetition range. ...
Born, DP, Stöggl, T, Petrov, A, Burkhardt, D, Luethy, F, and Romann, M. Analysis of freestyle swimming sprint start performance after maximal strength or vertical jump training in competitive female and male junior swimmers. J Strength Cond Res XX(X): 000-000, 2019-To investigate the freestyle swimming sprint start performance before and after 6 weeks of maximal strength compared with vertical jump training. With a between-group repeated-measure design, 21 junior swimmers (12 female and 9 male) competing in national and international championships performed 2 weekly sessions of either maximal strength (heavy-loaded back squat and deadlift exercise) or vertical jump training (unloaded box jumps) for 6 weeks during the precompetition phase of the seasonal main event. Session ratings of perceived exertion were used to compare the load of both training programs. Before and after the training period, sprint start performance was investigated on a starting block equipped with force plates synchronized to a 2-dimensional motion capture system. Total training load did not differ between the 2 groups. Sprint start performance and most kinematic and kinetic parameters remained unaffected. In pooled data of the U17 swimmers, however, 5-m, 15-m, and 25-m split times were improved with maximal strength (p 5 0.02, 0.03, and 0.01), but not with vertical jump training (p 5 0.12, 0.16, and 0.28). Although there was no global effect, focus on the subgroup of U17 swimmers showed an improved sprint start performance with 2 sessions of maximal strength training integrated into a 16-hour training week. Although outcomes of the conditioning program seemed to be affected by the training history and performance level of the athletes involved, strength and conditioning coaches are encouraged to introduce maximal strength training at a young age.
... The back squat (SQ) is one of the most widely used and effective resistance training (RT) exercises for strengthening the lower-limb, protecting against injuries and improving athletic performance (Hartmann, Wirth, & Klusemann, 2013). In the last three decades, numerous publications have found that increases in lower-body strength following SQ training transfer positively to functional athletic performance in short-duration actions that demand maximal voluntary contractions, such as sprinting and vertical jumping (Hartmann et al., 2012;Seitz, Reyes, Tran, de Villarreal, & Haff, 2014;Suchomel, Nimphius, & Stone, 2016;Wirth et al., 2016). ...
... In addition, training at larger depths (P-SQ and F-SQ) has been suggested to increase muscular and tendinous injuries, especially in the knee (Escamilla, Fleisig, Lowry, Barrentine, & Andrews, 2001). However, contrary to these common beliefs, recent studies propose that prolonged RT interventions involving P-SQ or F-SQ maximize the neuromuscular and functional performance in novice (Bloomquist et al., 2013) and well-trained athletes (Hartmann et al., 2012), and even minimize the risk of injury to passive tissues compared to shorter ROM (Hartmann et al., 2013). ...
... Only two studies have examined the effects of training at different SQ depths on strength and functional performance on well-trained and experienced athletes (Hartmann et al., 2012;Rhea et al., 2016). In both studies, maximum strength, jump height and sprint performance were evaluated after a periodized RT programme (using loads from 10RM to 2RM during 10-16 wk) in groups training at different squatting depths. ...
The choice of the optimal squatting depth for resistance training (RT) has been a matter of debate for decades and is still controversial. In this study, fifty-three resistance-trained men were randomly assigned to one of four training groups: full squat (F-SQ), parallel squat (P-SQ), half squat (H-SQ), and Control (training cessation). Experimental groups completed a 10-week velocity-based RT programme using the same relative load (linear periodization from 60% to 80% 1RM), only differing in the depth of the squat trained. The individual range of motion and spinal curvatures for each squat variation were determined in the familiarization and subsequently replicated in every lift during the training and testing sessions. Neuromuscular adaptations were evaluated by one-repetition maximum strength (1RM) and mean propulsive velocity (MPV) at each squatting depth. Functional performance was assessed by countermovement jump, 20-m sprint and Wingate tests. Physical functional disability included pain and stiffness records. F-SQ was the only group that increased 1RM and MPV in the three squat variations (ES = 0.77–2.36), and achieved the highest functional performance (ES = 0.35–0.85). P-SQ group obtained the second best results (ES = 0.15–0.56). H-SQ produced no increments in neuromuscular and functional performance (ES = −0.11–0.28) and was the only group reporting significant increases in pain, stiffness and physical functional disability (ES = 1.21–0.87). Controls declined on all tests (ES = 0.02–1.32). We recommend using F-SQ or P-SQ exercises to improve strength and functional performance in well-trained athletes. In turn, the use of H-SQ is inadvisable due to the limited performance improvements and the increments in pain and discomfort after continued training.
... The squat is widely used as an estimate of leg strength (6,10,14,18,22,(32)(33)(34) and has been shown to produce greater gains in speed-strength performance (32,33). Importantly, it should be noted that a squatting depth of at least parallel should be achieved to maximize these gains (14) and reduce stress on the vertebral column (13,15) while securing that leg strength is the primary determinant of the squatting performance (5). ...
... The squat is widely used as an estimate of leg strength (6,10,14,18,22,(32)(33)(34) and has been shown to produce greater gains in speed-strength performance (32,33). Importantly, it should be noted that a squatting depth of at least parallel should be achieved to maximize these gains (14) and reduce stress on the vertebral column (13,15) while securing that leg strength is the primary determinant of the squatting performance (5). ...
... After an individual warm-up, 1RM was determined in 5 attempts (at most) with 5 minutes of rest between trials. The test set up was based on the procedure described by Hartmann et al. (14). Berger and Hardage (1) have reported a test-retest reliability of r = 0.98. ...
Möck, S, Hartmann, R, Wirth, K, Rosenkranz, G, and Mickel, C. Relationship between maximal dynamic force in the deep back squat and sprinting performance in consecutive segments up to 30 m. J Strength Cond Res XX(X): 000-000, 2018-The sprint (in track and field athletics) is characterized by a fluent transition from predominantly knee extending musculature during the initial acceleration phase toward dominance of the hamstring muscle group thereafter. Because of this change in technique, it can be assumed that there is a decrease of correlation of the maximal dynamic force of the deep back squat and sprinting performance with increasing distance. Therefore, sprinting performance for consecutive intervals (0-5, 5-10, 10-15, 15-20, 20-25, and 25-30 m) as well as the 1 repetition maximum (1RM) were determined. Our results show statistically significant (p < 0.01) correlations for both the relationships with the absolute 1RM (r = -0.614 to -0.808) and the relative 1RM (r = -0.646 to -0.749). However, the expected decrease in correlation over distance was not found. The results show that the maximal dynamic force of hip and knee extensors are a basic performance requirement in short-distance sprinting and should be considered in training recommendations.
... If transfer of training effects is solely dictated by specificity of ROM, one would consider it might be unnecessary to squat any deeper than the ROM encountered in volleyball. However, several studies (2,6) suggested that the deep squat improved vertical jump performance more than the shallow squat. The purpose of this article was to provide readers the rationale as to why our athletes train with deep squats. ...
... One of the main purposes of our strength training is to improve vertical jump performance. In our knowledge, four studies (2,6,11,12) have investigated the differential training effects of deep versus shallow squats on vertical jump performance to date, and two studies (2,6) reported training with the deep squat was significantly more effective than that with the shallow squat. ...
... One of the main purposes of our strength training is to improve vertical jump performance. In our knowledge, four studies (2,6,11,12) have investigated the differential training effects of deep versus shallow squats on vertical jump performance to date, and two studies (2,6) reported training with the deep squat was significantly more effective than that with the shallow squat. ...
The squat is one of the most common exercises for strengthening lower extremities. While this exercise can be performed with shallower or deeper range of motion, our athletes train with deep squats (front of thigh below parallel to the floor, or 120-140° knee flexion) in the Japan Volleyball Women’s National Team. It is because literature has suggested that the deep squat improved vertical jump performance more than the shallow squat. This article synthesizes available literature and provides readers our rationale of why athletes should train with deep squats.
... Durch eine Vielzahl von Studien kann belegt werden, dass Veränderungen der Maximalkraft einen direkten Einfluss auf die Schnellkraft (u.a. Arabatzi, et al., 2010;Augustsson et al., 1998;Chelly et al., 2009;Christou et al., 2006;Hartmann et al., 2012;Kotzamanidis et al., 2005;Lamont et al., 2009;Lockie et al., 2012;Maio Alves et al., 2010;Moss et al., 1997;RØnnestad et al., 2008;Wirth, 2006/07) und die Kraftausdauer (u.a. Dorgo et al., 2009;Naclerio et al., 2009) haben. ...
... Durch eine maximale willkürliche Kontraktion können nicht alle motorischen Einheiten zeitgleich aktiviert werden. Somit repräsentiert der unter diesen Bedingungen ermittelte Maximalkraftwert nicht die maximale Kraft die das neuro-muskuläre System entfalten kann, sondern nur den Teil, welcher von den Fähigkeiten des jeweiligen Individuums abhängt, sein muskuläres Potential auszuschöpfen (Wirth et al., 2012). ...
... B. Fußball, Speer, Kugel) oder den Gegner (Zweikampfsportarten) mit dem Ziel einer hohen Endgeschwindigkeit maximal beschleunigen zu können. Somit ist Schnellkraft die Fähigkeit des neuromuskulären Systems innerhalb eines vorgegebenen Zeitfensters einen möglichst großen Kraftimpuls zu produzieren (Schmidtbleicher, 2003 (Wirth et al., 2012). Je kürzer der ...
... Relationships of jumping performance in concentric and slow-reactive jumps like the squat jump (SJ) and the countermovement jump (CMJ) with maximum strength of the knee and hip extensors have been reported in previous studies (Blackburn & Morrissey, 1998;Chelly et al., 2009;Comfort et al., 2014;Hendrick & Anderson, 1996;Nuzzo et al., 2008;Peterson et al., 2006;Santos & Janeira, 2012;Vanezis & Lees, 2005;Wisloff et al., 2004) and show high consistency. High, significant correlations (r = 0.69-0.85) in different squat variations with jumping performance in CMJ, SJ, and jump-and-reach test have been shown over the decades (Blackburn & Morrissey, 1998;Comfort et al., 2014;Hartmann et al., 2012;Nuzzo et al., 2008;Peterson et al., 2006;Wirth et al., 2016;Wisloff et al., 2004). ...
... After an individual warm-up, 1 RM was determined in 5 attempts (at most) with 5 min of rest between trials. The test set up was based on the procedure described by Hartmann et al. (2012). Both the absolute and the relative 1RM (absolute 1RM/body mass) were determined. ...
Vertical jumping performance is of high importance for various individual and team sports. Movement patterns utilizing a stretch shortening cycle are of particular interest. Despite their involvement in every vertical jump variation, the importance of the plantar flexors’ dynamic maximum strength for jumping performance has not been investigated yet. Therefore, the aim of this study is to examine the relationship between plantar flexion strength and different vertical jump variations. The present study examines the correlation of maximum strength in the standing calf raise and in the squat with performance in the vertical jumping forms squat jump (SJ), countermovement jump (CMJ), and drop jump (DJ) from different heights in 56 physical education students. The one-repetition maximum (1 RM) in the standing calf raise shows moderate to high (p < 0.01) correlations for SJ and CMJ (r = 0.575–0.659, and r = 0.565–0.708, respectively). The DJ revealed weak to medium correlations (p < 0.01) with the dynamic maximum strength of the plantar flexors (r = 0.362–0.573). A comparison of the strongest and weakest subjects revealed significant differences between groups with the stronger participants displaying greater jumping performance in all tests. In addition, squat 1 RM was significantly correlated (p < 0.05) with DJ performance. It can be concluded that the strength of the plantar flexors displays a relevant factor for vertical jumping performance in SJ, CMJ, and DJ that supports the main propulsive mechanisms.
... Execution of the squat jump: Subjects performed a barefoot squat jump on a non-deformable surface. The starting position was standing with a~90 knee flexion,~100 hip flexion and tiptoes facing forward (Figure 2), as described elsewhere [20,21]. During all phases of the jump, the hands remain on the hips, in order to eliminate any influence of the arms during execution. ...
... Execution of the squat jump: Subjects performed a barefoot squat jump on a non-deformable surface. The starting position was standing with a ~90° knee flexion, ~100° hip flexion and tiptoes facing forward (Figure 2), as described elsewhere [20,21]. During all phases of the jump, the hands remain on the hips, in order to eliminate any influence of the arms during execution. ...
The vertical jump is a complex movement where many factors are involved in the final result. Currently, how a specific exercise program for gluteal muscles can affect the vertical jump is unknown. So, the aim of this study was to examine the effect of a specific exercise program for the gluteal muscles on a vertical jump. Forty-nine amateur athletes completed an 8-week program. The experimental group received a specific gluteal muscle training program in addition to their regular training routine, whereas the control group received their regular training routine. Jump height, flight time, speed and power were assessed (baseline, postintervention, and 4-week follow-up). Repeated-measures analyses of variance were conducted with ∝ ≤ 0.05. We calculated Eta squared effect sizes with 95% confidence intervals. Measurements at 8 weeks revealed significant increases in the experimental group compared to the control group for the values: jump height (p < 0.05) (experimental group = 17.15%; control group = 3.09%), flight time (p < 0.001) (experimental group = 7.98%; control group = 3.52%), speed (p < 0.01) (experimental group = 1.96%; control group = 1.83%) and power (p < 0.05) (experimental group = 4.43%; control group = 0.32%). However, at follow-up, these changes were not maintained. These data suggest that this specific training protocol for the gluteal muscles is effective in order to improve vertical jump performance in amateur athletes who use the vertical jump in their routine training habits.
... Resistance training is a common form of exercise for athletes and physically active people. A large and growing body of research has investigated the influence of the range of motion (ROM) during different resistance exercises and the specific neuromuscular adaptations they induce (Hartmann et al., 2012;Bloomquist et al., 2013;Martínez-Cava et al., 2019;Pallarés et al., 2020;Schoenfeld and Grgic, 2020). The available research has analyzed the effects of full (allowed by the standard barbell) or partial ROM during the bench press (BP) exercise on acute (Krzysztofik et al., 2020) as well as chronic changes in performance (Martínez-Cava et al., 2019). ...
... Moreover, the manipulation of the ROM during resistance exercises is a strategy commonly used among strength-trained athletes according to the principle of specificity (Schoenfeld and Grgic, 2020). However, recent evidence indicates that performing resistance exercises with a full ROM provides a greater stimulus, and leads to greater performance improvements in comparison to lifting with a limited ROM (Hartmann et al., 2012;Bloomquist et al., 2013;Martínez-Cava et al., 2019;Pallarés et al., 2020). Furthermore, Martínez-Cava et al. (2019) found that the greater the ROM used during the BP exercise, the greater improvements in maximum strength, and in the whole load-velocity spectrum in recreational and well-trained athletes. ...
The aim of this study was to compare the electromyographic activity between the standard and cambered bar during the bench press (BP) exercise. Twelve resistance-trained males performed the flat BP with a standard and a cambered bar at selected loads (50%, 70% and 90% 1RM). Muscle activity assessed by surface electromyography (sEMG) was recorded for the pectoralis major, anterior deltoid, and the lateral and long heads of the triceps brachii during each attempt. A three-way repeated measures ANOVA indicated statistically significant main interaction for bar × load × muscle (p<0.01); bar × load (p<0.01); bar × muscle (p<0.01); load × muscle (p<0.01). There was also a main effect for the bar (p<0.01); load (p<0.01); and muscle group (p<0.01). The post-hoc analysis for the main multiple interaction effect of bar × load × muscle group showed a statistically significant increase in sEMG for the standard bar in the pectoralis major compared to the cambered bar at 50%1RM (p<0.01) and 90%1RM (p<0.01), as well as in the triceps brachii long at 90%1RM (p<0.01). Furthermore, a statistically significant decrease in sEMG was registered for the standard bar in the anterior deltoid compared to the cambered bar at 90%1RM (p=0.02). The results indicated that the cambered bar was superior in activating the anterior deltoid muscle compared to the standard bar during the BP exercise, whereas the standard bar provided higher pectoralis major and triceps brachii long head sEMG activity at 90%1RM
... The choice of the most effective range of motion (ROM) to produce specific neuromuscular adaptations after a given resistance training (RT) program has been a matter of debate (1,11,18,19,28). In addition to the conventional full ROM exercises, some authors consider training at partial ROM beneficial, since it allows lifting higher loads, decreases the neural inhibition, increases the force produced, and improves the coordination of primary and stabilizing muscles (2,(18)(19)(20). ...
... In contrast to this assumption, a recent and exhaustive research has found that lower ROMs generate limited performance improvements in comparison with full ROMs, besides increments in pain and discomfort after a prolonged RT program in the back squat exercise (24). These results concur with previous findings concluding that full squat maximizes neuromuscular and functional performance both in novice (1) and welltrained athletes (11). Although this evidence has been proven in essential lower-limb RT exercises such as the squat, the effects of training full and partial ROM in the bench press (BP), which is probably the most common upper-limb exercise, are still under controversy (23). ...
Martínez-Cava, A, Hernández-Belmonte, A, Courel-Ibáñez, J, Morán-Navarro, R, González-Badillo, JJ, and Pallarés, JG. Bench press at full range of motion produces greater neuromuscular adaptations than partial executions after prolonged resistance training. J Strength Cond Res XX(X): 000-000, 2019-Training at a particular range of motion (ROM) produces specific neuromuscular adaptations. However, the effects of full and partial ROM in one of the most common upper-limb exercises such as the bench press (BP) remain controversial. In this study, 50 recreationally to highly resistance trained men were randomly assigned to 1 of 4 training groups: full bench press (BPFULL), two-thirds bench press (BP2/3), and one-third bench press (BP1/3) and control (training cessation). Experimental groups completed a 10-week velocity-based resistance training program using the same relative load (linear periodization, 60-80% 1 repetition maximum [1RM]), only differing in the ROM trained. Individual ROM for each BP variation was determined in the familiarization and subsequently replicated in every lift during training and testing sessions. Neuromuscular adaptations were evaluated by 1RM strength and mean propulsive velocity (MPV). The BPFULL group obtained the best results for the 3 BP variations (effect size [ES] = 0.52-1.96); in turn, partial BP produced smaller improvements as the ROM decreased (BP2/3: ES = 0.29-0.78; BP1/3: ES = -0.01 to 0.66). After 10-week of training cessation, the control group declined in all neuromuscular parameters (ES = 0.86-0.92) except in MPV against low loads. Based on these findings, the BPFULL stands as the most effective exercise to maximize neuromuscular improvements in recreational and well-trained athletes compared with partial ROM variations.
... In turn, Hartmann et. al [11] and Contreras B. [3] indicate that, as regards the shaping of muscles acting during squats it is necessary to perform the entire movement during the squat. A more clear division among scientists is the one concerning assessments of dierences between front and back squats. ...
... In addition, the author emphasized that the full squat increases the risk of damage to the ligamentous apparatus within the knee joint and the meniscus. Hartmann et al. [11] stated that the depth of squats was an important variable related to the eective training of squats. Contreras B. [3] indicated that, as regards the shaping of the muscles active during squats, when making squats it is necessary to perform movements within the entire range. ...
The research work aimed to identify and analyse reactions in the joints of the lower limb as well as in the intervertebral joints of the lumbar spine when lifting weights and making a squat. The determination of loads of the skeletal-muscular system involved the performance of simulations in the AnyBody software programme. Input data used in the research-related tests came from the tests concerning the kinematics of weightlifting by a weightlifter. The use of mathematical modelling and static optimisation methods made it possible to identify resultant responses in the joints in individual positions of a squat made under various external loads. The highest resultant responses in all of the joints subjected to analysis were identified at an angle of \(135^{\circ }\) in knee joints. As a result, it is important to pay attention during training not to stop moving during an exercise at the above-named angle.
... However, this observation does not seem to apply to power, because we did not observe any improvement in CMJ performance in the RT + CT or RT + HIIT group. Heavy-load squat training alone is associated with increased CMJ performance (Hartmann et al., 2012;Helgerud et al., 2011), and our results therefore suggest that power gains were compromised when endurance training was added to the RT program. This finding is consistent with those of previous studies on less-trained individuals (Chtara et al., 2008;Fyfe et al., 2016). ...
... However, it should be pointed out that the RT program used in the present study was performed to failure or close to failure. This is an effective program for improving strength and to some degree power (Davies et al., 2016;Hartmann et al., 2012;Helgerud et al., 2011;Hoffman et al., 2009). However, "non-failure" protocols have been shown to be more efficient for power improvements (Pareja-Blanco et al., 2017) and it can therefore not be ruled out that the absence of CMJ performance increments was a consequence of how the RT program was designed. ...
The effects of concurrent strength and endurance training have been well studied in untrained and moderately-trained individuals. However, studies examining these effects in individuals with a long history of resistance training (RT) are lacking. Additionally, few studies have examined how strength and power are affected when different types of endurance training are added to an RT protocol. The purpose of the present study was to compare the effects of concurrent training incorporating either low-volume, high-intensity interval training (HIIT, 8-24 Tabata intervals at ~150% of VO2max) or high-volume, medium-intensity continuous endurance training (CT, 40-80 min at 70% of VO2max), on the strength and power of highly-trained individuals. Sixteen highly-trained ice-hockey and rugby players were divided into two groups that underwent either CT (n = 8) or HIIT (n = 8) in parallel with RT (2-6 sets of heavy parallel squats, > 80% of 1RM) during a 6-week period (3 sessions/wk). Parallel squat performance improved after both RT + CT and RT + HIIT (12 ± 8% and 14 ± 10% respectively, p < 0.01), with no difference between the groups. However, aerobic power (VO2max) only improved after RT + HIIT (4 ± 3%, p < 0.01). We conclude that strength gains can be obtained after both RT + CT and RT + HIIT in athletes with a prior history of RT. This indicates that the volume and/or intensity of the endurance training does not influence the magnitude of strength improvements during short periods of concurrent training, at least for highly-trained individuals when the endurance training is performed after RT. However, since VO2max improved only after RT + HIIT and this is a time efficient protocol, we recommend this type of concurrent endurance training.
... In the last three decades, numerous publications have found that increases in lower-body strength following squat training transfer positively to athletic performance in shortduration actions that demand maximal neuromuscular activation such as sprinting and vertical jumping (Hartmann et al., 2012;Ronnestad, Kojedal, Losnegard, Kvamme, & Raastad, 2012;Seitz, Reyes, Tran, de Villarreal, & Haff, 2014;Wirth et al., 2016). Recent studies have also observed greater functional and specific performance improvements in medium to long distance athletes (e.g. ...
... @PallaresJG Human Performance and Sports Science Laboratory, Faculty of Sport Sciences, University of Murcia, C/Argentina s/n. Santiago de la Ribera, Murcia, Spain performance of well-trained athletes (Bloomquist et al., 2013;Drinkwater, Galna, McKenna, Hunt, & Pyne, 2007;Hartmann et al., 2012;Weiss, Frx, Wood, Relyea, & Melton, 2000), and can even minimize the risk of injury (Hartmann et al., 2013) when compared to RT programs in which the SQ is performed to shorter ROM. ...
This study aimed to compare the load-velocity and load-power relationships of three common variations of the squat exercise. 52 strength-trained males performed a progressive loading test up to the one-repetition maximum (1RM) in the full (F-SQ), parallel (P-SQ) and half (H-SQ) squat, conducted in random order on separate days. Bar velocity and vertical force were measured by means of a linear velocity transducer time-synchronized with a force platform. The relative load that maximized power output (Pmax) was analyzed using three outcome measures: mean concentric (MP), mean propulsive (MPP) and peak power (PP), while also including or excluding body mass in force calculations. 1RM was significantly different between exercises. Load-velocity and load-power relationships were significantly different between the F-SQ, P-SQ and H-SQ variations. Close relationships (R² = 0.92–0.96) between load (%1RM) and bar velocity were found and they were specific for each squat variation, with faster velocities the greater the squat depth. Unlike the F-SQ and P-SQ, no sticking region was observed for the H-SQ when lifting high loads. The Pmax corresponded to a broad load range and was greatly influenced by how force output is calculated (including or excluding body mass) as well as the exact outcome variable used (MP, MPP, PP).
... The back squat is a popular resistance training exercise used for developing the lower body muscles. The back squat increases lower body strength, improves lower body rate of force development, and is a necessary component in many athletic and clinically based populations (11,24). In therapeutic environments, squat depths are typically performed using between 0 and 60° of knee flexion (half and quarter squats) as these ranges of motion result in the least amount of patellofemoral compressive forces observed (16). ...
... In therapeutic environments, squat depths are typically performed using between 0 and 60° of knee flexion (half and quarter squats) as these ranges of motion result in the least amount of patellofemoral compressive forces observed (16). However, deeper squat depths have been encouraged to engage the entire lower body musculature (9,24). For example, powerlifters typically train to parallel depths, defined as when the inguinal crease falls below the proximal patella at approximately 110° of knee flexion, and Olympic weightlifters often train to full depth, defined as when the back of the hamstrings come into complete contact with the calves at approximately 135° of knee flexion (16,23,30,42). ...
The back squat exercise is typically practiced with varying squat depths and barbell loads. However, depth has been inconsistently defined, resulting in unclear safety precautions when squatting with loads. Additionally, females exhibit anatomical and kinematic differences to males which may predispose them to knee joint injuries. The purpose of this study was to characterize peak knee extensor moments (pKEMs) at three commonly practiced squat depths of above parallel, parallel, and full depth, and with three loads of 0% (unloaded), 50%, and 85% depth-specific one repetition maximum (1RM) in recreationally active females. Nineteen females (age, 25.1 ± 5.8 years; body mass, 62.5 ± 10.2 kg; height, 1.6 ± 0.10 m; mean ± SD) performed squats of randomized depth and load. Inverse dynamics were used to obtain pKEMs from three-dimensional knee kinematics. Depth and load had significant interaction effects on pKEMs (p = 0.014). Significantly greater pKEMs were observed at full depth compared to parallel depth with 50% 1RM load (p = 0.001, d = 0.615), and 85% 1RM load (p = 0.010, d = 0.714). Greater pKEMs were also observed at full depth compared to above parallel depth with 50% 1RM load (p = 0.003, d = 0.504). Results indicate effect of load on female pKEMs do not follow a progressively increasing pattern with either increasing depth or load. Therefore, when high knee loading is a concern, individuals must carefully consider both the depth of squat being performed and the relative load they are using.
... In addition to the manipulation of variables intrasession, coaches program exercises within periodized programs to vary the intensity of the training stimuli. Regarding squat movements, the exercise stimulus may be varied based on the depth and variation of the squat [66], as well as the load that is prescribed. As a result, the force-velocity characteristics of the training stimulus will be modified, but the athlete's force-velocity profile may be fully developed. ...
Load management is an extremely important subject in fatigue control and adaptation processes in almost all sports. In Olympic Weightlifting (OW), two of the load variables are intensity and volume. However, it is not known if all exercises produce fatigue of the same magnitude. Thus, this study aimed to compare the fatigue prompted by the Clean and Jerk and the Snatch and their derivative exercises among male and female participants, respectively. We resorted to an experimental quantitative design in which fatigue was induced in adult individuals with weightlifting experience of at least two years through the execution of a set of 10 of the most used lifts and derivatives in OW (Snatch, Snatch Pull, Muscle Snatch, Power Snatch, and Back Squat; Clean and Jerk, Power Clean, Clean, High Hang Clean, and Hang Power Clean). Intensity and volume between exercises were equalized (four sets of three repetitions), after which one Snatch Pull test was performed where changes in velocity, range of motion, and mean power were assessed as fatigue measures. Nine women and twelve men participated in the study (age, 29.67 ± 5.74 years and 28.17 ± 5.06 years, respectively). The main results showed higher peak velocity values for the Snatch Pull test when compared with Power Snatch (p = 0.008; ES = 0.638), Snatch (p < 0.001; ES = 0.998), Snatch Pull (p < 0.001, ES = 0.906), and Back Squat (p < 0.001; ES = 0.906) while the differences between the Snatch Pull test and the derivatives of Clean and Jerk were almost nonexistent. It is concluded that there were differences in the induction of fatigue between most of the exercises analyzed and, therefore, coaches and athletes could improve the planning of training sessions by accounting for the fatigue induced by each lift.
... Enhancement has been noted for measures of maximum dynamic and isometric strength, explosive strength (RFD) as well as running and jumping have been noted with the use of training squats of varying amplitude [102][103][104]. Evidence also indicates that using exercises with larger ampli-tudes may augment positive effects on sport movements by better mimicking sport-specific amplitudes [105,106]. ...
Specificity has two major components: A strength-endurance continuum (S-EC) and adherence to principles of Dynamic Correspondence. Available evidence indicates the existence of the S-EC continuum from two aspects. Indeed, the S-EC exists, particularly if work is equated as a high load low repetition scheme at one end (strength stimulus) and high volume (HIEE stimulus) at the other. Furthermore, some evidence also indicates that the continuum as a repetition paradigm with high-load, low repetition at one end (strength stimulus) and a high repetition, low load at the other end. The second paradigm is most apparent under three conditions: (1) ecological validity—in the real world, work is not equated, (2) use of absolute loads in testing and (3) a substantial difference in the repetitions used in training (for example 2–5 repetitions versus ≥10 repetitions). Additionally, adherence to the principles and criteria of dynamic correspondence allows for greater “transfer of training” to performance measures. Typically, and logically, in order to optimize transfer, training athletes requires a reasonable development of capacities (i.e., structure, metabolism, neural aspects, etc.) before more specific training takes place
... In addition to the manipulation of variables intrasession, coaches program exercises within periodized programs to vary the intensity of the training stimuli. Regarding squat movements, the exercise stimulus may be varied based on the depth and variation of the squat [66], as well as the load that is prescribed. As a result, the force-velocity characteristics of the training stimulus will be modified, but the athlete's force-velocity profile may be fully developed. ...
Load management is an extremely important subject in the control of fatigue and adaptation process in almost all sports. In Olympic Weightlifting (OW), some of the load variables are known, namely intensity and volume. However, the type of exercise remains unknown in specific terms, this is because empiricism tells us that some exercises induce greater fatigue than others, nonetheless we do not know specifically the value for this quantification. Thus, this work intends to evaluate the amount of fatigue provoke by various types of OW exercises. We resorted to an experimental quantitative design, where we induced fatigue in adult individuals with weightlifting experience of at least 2 years, through the execution of a set of 10 of the most used exercises in OW, in which the intensity and volume between them were equalized (4 sets of 3 repetitions), after which a Snatch Pull test was performed and changes in maximum and medium velocity, range of motion and medium power were evaluated as fatigue measurement, between before and after the protocol of each exercise through the linear transductor Vitruve (Vitruve encoder; Madrid, Spain). Nine women and 12 men have participated in the study (age, 29.67±5.74years and 28.17±5.06years; height, 158.78±6.70cm and 174.50±6.07cm; body weight, 60.84±7.34kg and 79.46±5.32kg; %body fat, 17.76±7.63% and 16.98±5,14%, respectively). For the total sample, significant differences were found in the range of motion (ROM) of Snatch Pull, Snatch and Back Squat (respectively, p<0.001 and ES=0.986; p=0.003 and ES=0.731 ; p=0.021 and ES=0.547) and also on C&J ROM (p=0.015 and ES=0.582), in the mean power variable, significant differences were found in Power Snatch, Snatch, Snatch Pull and Back Squat and C&J (respectively, p=0.043 and ES=0.472; p=0.048 and ES=0.460; p=0.003 and ES=0.729; p=0.009 and ES=0.636 ; p=0.037 and ES=0.488), in peak velocity, significant differences were found in Power Snatch, Snatch, Snatch Pull and Back Squat (respectively, p=0.008 and ES=0.638; p<0.001 and ES=0.998; p<0.001 and ES=0.906 ; p<0.001 and ES=0.906), in the mean velocity variable, significant differences were found in Snatch Pull and Back Squat (respectively, p=0.030 and ES=0.509; p=0.003 and ES=0.727). When genders were analyzed separately, on the female group, significant differences were noticed in Snatch ROM, Snatch Pull and Back Squat (respectively, p=0.006 and ES=1.218; p=0.001 and ES=1.776; p=0.002 and ES=1.474), in the mean power variable, significant differences were found in Snatch, Snatch Pull and Back Squat (respectively, p=0.006 and ES=1.227; p=0.002 and ES=1.512 ; p=0.001 and ES=1.679), at peak velocity significant differences were revealed in Snatch, Snatch Pull and Back Squat (respectively, p=0.002 and ES=1.469; p=0.005 and ES=1.258; p<0.001 and ES=2.058), for the mean velocity variable, significant differences were found in Snatch, Snatch pull and Back squat (respectively, p=0.006 and ES=1.228; p=0.003 and ES=1.372 ; p=0.001 and ES=1.660). In the male group, differences were found in the ROM of Snatch Pull, C&J and Clean (respectively, p=0.042 and ES=0.663; p=0.004 and ES=1.033; p=0.020 and ES=0.786) also, significant differences in mean power were only found in C&J (p=0.009 and ES=0.910, at peak velocity were revealed significant differences in Power Snatch, Snatch and Snatch Pull (respectively, p=0.009 and ES=0.910; p=0.025 and ES=0.745; p=0.039 and ES=0.675), the mean velocity showed significant differences only in the C&J (p=0.011 and ES=0.876). It is thus concluded that there are differences in the induction of fatigue between most of the exercises analyzed, and that the female gender seems to be more resistant to fatigue than the male gender, in relation to exercises derived from C&J, however in the exercises derived from snatch the reverse seems to happen in most variables except at maximum speed, in which both genders present similar fatigue in the analyzed exercises.
... The SLS could be used as part of an assessment in patients with femoral acetabular impingement (FAI), due to the populations reluctance to perform hip flexion on the affected leg [30,32]. Additionally, the increased sagittal plane demand and depth of squat during the SLS make it an optimal exercise when training to increase performance during jumping tasks [33]. ...
The single leg squat (SLS), forward step down (FSD), and lateral step down (LSD) are
clinically reliable movement screens for identifying motion imbalances. The current understanding for the kinematic profiles of each task is limited to discrete time points such as peak knee flexion. However, analyses of the entire movement would better aid clinicians when selecting the appropriate task for rehabilitation or movement screen purposes. The current study used Statistical Parametric Mapping to ascertain differences in the kinematic waveforms for the entire duration of each task. The trunk, pelvis, hip, and knee were analyzed in the sagittal and frontal planes. Data for each variable and task were analyzed from 0–100% of the movement. Primary findings indicated that the
FSD provoked a greater magnitude of knee abduction than the SLS and LSD from 26–66% of the movement. The SLS generated the greatest amounts of trunk, pelvic, and hip flexion for the entirety of the movement. The LSD elicited the least amount of ipsilateral trunk lean (90–100%). Thus, the FSD may be optimal for assessing frontal plane knee motion as a screen for injury risk, while the SLS has potential to place increased sagittal plane demand on the muscles of the hip.
... • In den vorliegenden Studien: Verwendung der Halbkniebeuge ➢ Besser: Tiefkniebeuge (Hartmann et al., 2012;Pallarés et al., 2020) in Kombination mit Training der Sprinttechnik und Plyometrics? (Cronin & Hansen, 2005;Franco-Márquez et al., 2015;Ronnestad et al., 2008) ➢ Niedrigere Lasten → reduzierte Verletzungsgefahr (z.B. ...
... This is potentially due to subjects having inadequate technique, and concerns regarding lack of mobility and injury (9), or the belief that it is a more sport-specific range of motion (32). However, full (135-140°knee flexion) and parallel (110-120°knee flexion) squats have been shown to improve vertical jump, acceleration, and load-velocity characteristics more so than half-squats and quarter-squats (2,15,31). ...
The aims of this study were to investigate the impact of high-intensity, low-volume (HRT) vs. moderate-intensity, high-volume resistance training (MRT) vs. soccer training only (CON) on changes in strength, power, and speed, and to compare delayed onset muscle soreness (DOMS) between groups in male academy soccer players (ASP). Twenty-two ASP (age: 18±1 years) were assigned to either HRT (n=8), MRT (n=7) or CON (n=7). HRT completed 2 sets of 4 repetitions parallel back squat (PBS) repetitions at 90% 1RM, while MRT performed 3 sets of 8 repetitions PBS repetitions at 80% 1RM, both once a week for six-weeks in-season, alongside regular soccer training. All groups completed the following pre- and post-training assessments: 3RM PBS; bilateral vertical and horizontal countermovement jumps (CMJ); squat jump (SJ); 30m sprint. DOMS was assessed via visual analogue scale throughout training. HRT and MRT experienced similar increases compared to CON in absolute PBS 3RM (p<0.001), SJ height (p=0.001), CMJ height (p=0.008) following training. There was a greater increase in PBS 3RM relative to body mass following HRT than MRT and CON (p=0.001) and horizontal CMJ distance improved in HRT but not in MRT or CON (p=0.011). There was no change in 10m, 20m or 30m sprint performance in any group. HRT volume was 58±15% lower than that of MRT (p<0.001) and DOMS measured throughout training did not differ between groups (p=0.487). These findings suggest that one HRT session a week may be an efficient method for improving strength and power in ASP in-season with minimal DOMS.
... The back-squat is one of the most effective exercises to strengthen the lower limbs and prevent injuries [16]. Additionally, lower-body strength gains following back-squat training have been shown to positively transfer to athletic performance during short duration high-intensity actions such as jumping and sprinting [17,18]. The back-squat exercise can be performed using the pause (i.e., a pause of 1-4 s is implemented between the lowering and lifting phases) or rebound techniques (i.e., the lifting phase is performed immediately after the lowering phase using the stretch-shortening cycle) [19,20]. ...
This study aimed to compare the between-session reliability of different performance variables during 2 variants of the Smith machine back-squat exercise. Twenty-six male wrestlers performed 5 testing sessions (a 1-repetition maximum [1RM] session, and 4 experimental sessions [2 with the pause and 2 with the rebound technique]). Each experimental session consisted of per-forming 3 repetitions against 5 loads (45-55-65-75-85% of the 1RM). Mean velocity (MV), mean power (MP), peak velocity (PV), and peak power (PP) variables were recorded by a linear position transducer (GymAware PowerTool). The best and average scores of the 3 repetitions were con-sidered for statistical analyses. The coefficient of variation (CV) ranged from 3.89% (best PV score at 55%1RM using the pause technique) to 10.29% (average PP score at 85%1RM using the rebound technique). PP showed a lower reliability than MV, MP, and PV (CVratio≥1.26). The relia-bility was comparable between the exercise techniques (CVratio=1.08) and between the best and av-erage scores (CVratio=1.04). These results discourage the use of PP to assess back-squat performance at submaximal loads. The remaining variables (MV, MP, or PV), exercise techniques (pause or rebound), and repetition criteria (best score or average score) can be indistinctly used due to their acceptable and comparable reliability.
... Following an individual warm up, 1RM was determined in 5 attempts (at most) with 5 min of rest between trials. The test set up was based on the procedure described by Hartmann et al. [14]. Berger and Hardage [5] have reported a test-retest reliability of r = 0.98. ...
PurposeMuscle strength and power are important requirements in many sports. The correlation of jumping performance as manifestation of muscle power and squatting one-repetition maximum (1RM) has been shown in several investigations. Correlations with maximum force in a linear isokinetic leg press are still pending. Since different testing devices produce different relationships and rotational isokinetic measurements show conflicting results, further evidence is needed.Methods
We investigated the correlation of isokinetic leg press force at 0.1 m/s and 0.7 m/s with squat 1RM and jumping performance in different vertical jumps.ResultsThe results show medium to strong, significant correlations for isokinetic force at 0.1 m/s with squat- and countermovement-jump performance, whereas isokinetic force at 0.7 m/s showed strong, significant correlations for both jumping tests. Drop jump performance (dropping heights: 20, 30, 40, and 50 cm, respectively) reveals weak to medium, significant correlations with isokinetic force at 0.1 m/s and weak, significant correlations with isokinetic force at 0.7 m/s. Squat 1RM displays strong relationships to isokinetic force with greater coefficients regarding higher movement speed in the isokinetic condition.Conclusion
The maximum strength of the leg extensors displays a basic requirement for vertical jumping with great motion in knee- and hip-joints and should be considered in training programs. For vertical jumps that are mainly generated via ankle motion, maximum strength of knee- and hip-extensors plays an indirect role to guarantee for performance-enhancing mechanisms. Additionally, in strength testing, different manifestations of strength performance should carefully be taken into account.
... ~2 s). Since the squatting depth influences the acute and chronic responses (Hartmann et al., 2012), the range of motion was matched in each exercise (i.e. until the thighs were parallel to the floor). Two devices were used for EOEs because they allowed more (VP) or less (YIT) freedom of movement and could produce different levels of activation and/or damage. ...
The aim of this study was to analyse the acute effects of a concentric exercise and two different eccentric overload exercises (EOEs) on blood markers of muscle damage (i.e. creatine kinase [CK], lactate dehydrogenase [LDH], myoglobin [Myo], and malondialdehyde [MDA]) and muscle contractile properties. Ten healthy, young (27 ± 1.5 years, 179 ± 6 cm, 78.7 ± 10.8 kg), physically active men (3.5 ± 1.9 h·w-1) randomly performed three training sessions using the following protocols: a half-squat (HS) as a concentric exercise, and exercises using Versapulley (VP) or YoYo isoinertial technology (YIT) as EOEs (4 x 7 repetitions with a 2 min rest interval between sets). Blood samples and tensiomyography measurements were obtained after each training session. Repeated measures analysis of variance (ANOVA) followed by the Tukey test was used to detect differences between the four time points of each variable. The standardized difference or effect size (ES, 90% confidence limit) in the selected variables was calculated using the basal SD. After all exercises, a greater activity of CK, LDH, and concentration of Myo, and MDA were found compared to baseline values (p < 0.05). A substantially greater activity of CK, LDH, and Myo concentration, but not MDA, were found after EOEs when compared to the HS protocol. Substantially lower tensiomyography results in the rectus femoris (RF) were reported, irrespective of the exercise mode performed. Also, no substantial differences were obtained in the biceps femoris (BF) between EOEs and the HS protocol. Time of contraction (Tc) in the RF was possibly to very likely lower in the HS in comparison to EOEs. Additionally, muscular displacement (Dm) in the RF was substantially lower in the HS compared to EOEs. VP produced higher concentrations of damage markers than YIT and concentric exercise did. Furthermore, tensiomyography variables showed similar activation in both exercises, although higher specific fatigue (in the RF) was registered in the traditional HS.
... The results of correlation between variables in our study (Ankle angle with each of the Time of Height BCG & and the Trunk angle) confirmed the previous findings of ; that the legs bent (knee angle around 110°) and feet wider suggest that the starting position is an automatic choice by the players in order to be ready to go to block all types of opponent sets (Roberto Lobietti, Fantozzi, and Merni 2006). Athletes should employ more strength training of lower limb extension, engaging small joint angles ( full squats) (Hartmann et al. 2012). ...
Aim: The study aims to conduct a kinematical analysis of blocking skill in volleyball and their relationships with the explosive force of lower limbs, for the athletes from the elite Algerian team.Methods: A total of 06 male Volleyball Players from the elite Algerian team as volunteers (Age: 25.66+3.32 yr, Length:198.00+3.68 cm, Weight: 86.66+6.62 kg). We used for kinematical analysis the software Dartfish9. For video capturing, we used three cameras (AEE Magic Cam) for record the performance during an Experimental competition, two CAMІ&П(X1m, Y, Z1.5m) were placed in the sides of volleyball Court, and CAMⅢ(X4.5m, Y1m, Z1.5m) behind the elite Algerian team. Also, two force Explosive tests were executed; Squat Jump (SJ) and Counter Movement Jump (CMJ). The data were analyzed in SPSS 22.0 program. Descriptive statistics (mean±SD) and P test for the correlations between variables studied.Results: Through the statistical analysis, there were significant correlations between values of CMJ test with both of the DHeightBCG (p<0.01), & DMax height (p<0.01), and between variable DMax height with each of the °Trunk (p<0.01), & °Knee (p<0.01), and DLowBCG (p<0.01), and DHeightBCG (p<0.01) respectively, at the 0.05 level. Also, between DLowBCG with °Trunk (p<0.01), and with °Knee (p<0.01).Conclusion: This study was able to produce results that are helpful to coaches when deciding when they are considering vertical jump heights during the performance of blocking skill in volleyball, through developing the technical aspect of the blocking skill by training players to improve the kinematical properties of a certain degree; especially, the angles of the lower limbs of the body, such as the angles of the trunk, knee, and ankle.
... This exercise has been proposed to be performed at different depths based on the premise that doing so induces different functional and morphological adaptations in the muscle-tendon complex (Bloomquist et al., 2013;Schoenfeld, 2010). For instance, a deeper back squat has been reported to be advantageous in developing lower limb strength (Bloomquist et al., 2013) and jumping height (Hartmann et al., 2012). Such strength gain is thought to occur do to a greater increase in skeletal muscle hypertrophy, as well as changes in the geometry of muscle fascicles, i.e., muscle architecture (Bloomquist et al., 2013;Schoenfeld, 2010). ...
This study investigated the relationship between back squat depth
capacity, ankle dorsiflexion resistance to stretch and maximal range of
motion (ROM), and Achilles tendon stiffness of healthy individuals
(n = 20). Squat depth capacity was assessed with 2D kinematic analysis.
Ankle dorsiflexion maximal ROM was assessed using a smartphone
digital goniometry (lunge test) and isokinetic dynamometry (prone
test). Ankle dorsiflexion resistance to stretch was assessed during the
prone test. Achilles tendon stiffness was estimated at rest [using shear
wave elastography (stiffness-SWE)] and during isometric contraction
through tendon force-length relationship (using B-mode sonography).
Squat depth was associated only with ankle dorsiflexion ROM in the
lunge test (r = 0.69, p = 0.001). Ankle dorsiflexion ROMin the lunge test was associated with the ankle resistance to stretch (r = 0.46, p = 0.050)
and Achilles tendon stiffness-SWE (r = 0.62, p = 0.005); and it was the
only variable different between individuals with low and high squat
depth capacity (p = 0.014). No other statistically significant associations
were found. In conclusion, back squat depth is associated with ankle 25
dorsiflexion ROM when the knee is flexed, without evident influence of
global joint and Achilles tendon mechanical properties.
... Furthermore, parallel squats are associated with greater jump performance, previously thought to result exclusively from improved agonist induced rate of force development. 38 Our data provides new evidence suggesting that the role of the squat exercise in improved jump performance may be due to enhanced dynamic trunk stability, while compounding the justification for squatting to parallel. ...
This study measured how back squat strength (1RM) affected trunk muscle activation in performing squats, squat jump (SJ) and countermovement jump (CMJ). Fifty males, completed two test sessions. Squat 1RM was tested first. Participants were assigned to three groups; (i) strong group (SG), (ii) middle group (MG) or (iii) weak group (WG), based on relative squat 1RM. Test 2, EMG data were collected for 4 trunk muscle sites; rectus abdominus, external oblique, lumbar sacral erector spinae and upper lumbar erector spinae while performing (3 reps) SJ, CMJ and squats at 65, 75 and 95% 1RM. Squat and jump phases were determined from a linear transducer and 30o tertiles for each phase, from a knee goniometer. Normalized root mean square RMS increased significantly with load for each muscle site in both squat phases. Trunk muscle activation was significantly lower in SG vs WG in eccentric and concentric squat phases. Concentric and flight phase RMS in both jumps was lower in SG vs WG. RMS increased significantly for each eccentric tertile and first concentric tertile. Greater squat strength is associated with lower trunk muscle activation in squats and jumps and trunk muscle activation was highest in the two deepest 30o squat segments. In conclusion, back squat strength training to parallel, where top of thighs are horizontal, is an effective method of developing dynamic trunk stability. This article is protected by copyright. All rights reserved.
... Whether females were limited in their ability to decrease knee and hip angles due to a deficit in power or other factors is unclear. If a strength deficit is considered as main reason for a weak countermovement in individuals, such athletes should employ more strength training of lower limb extension, engaging small joint angles (e.g., full squats) (Hartmann et al., 2012). It appears that males benefited from the larger torso incline generated during the backswing of the arms. ...
There are well-known biological differences between women and men, especially in technical-coordinative variations that contribute to sex differences in performance of complex movements like the most important offensive action in volleyball, the spike jump. The aim of this study was to investigate sex-dependent performance and biomechanical characteristics in the volleyball spike jump. Thirty female and male sub-elite volleyball players were analysed while striking a stationary ball with maximal spike jump height. Twelve MX13 Vicon cameras with a cluster marker set, two AMTI force plates, surface EMG, and a Full-Body 3D model in Visual3D were used. Main findings include sex differences (P< .05) in jump height (pη² = .73), approach [speed (pη² = .61), step length], transition strategy [plant angle, neuromuscular activation (pη² = .91), horizontal force maxima and impulses], acceleration distances [centre of mass displacement (pη² = .21), minimal knee and hip angles], use of torso and arms [incline, angular velocity (pη² = .23)]. Correlations support that the results cannot be explained fully by strength and power differences between sexes but represent the product of technical-coordinative variations. Their relevance is acknowledged for both sexes and numerous performance determinants displayed sex differences. The integration of such attributes into sex-specific training seems promising but its effect requires further investigation.
... In addition, the SQG showed medium to large effects on performance in the CMJ and MCV with both loads. These results agreed with the principle of specificity, since these variables had the same external force vector direction [33]. In addition, eight weeks of a back squat training program with loads ranging from 40% to 60% of the 1-RM showed potential beneficial effects on vertical jump height (∆ = 6.4 [3.5;9.2] ...
Hip thrust (HT) is a loaded bridging exercise that requires more hip extension than a back squat (SQ) does, while in a back squat, triple flex extension occurs. Due to the specificity of each exercise, it is claimed that HT gains can be better transferred to actions where hip extension occurs. In addition, strength improvements during squatting can be transferred in a greater way to vertical plane movement, such as vertical jumping. However, its effects on the performance of female soccer players are unclear. For this reason, the purpose of this study was to analyze a 7-week training program on performance variables using either HT or SQ exercises in female adolescent soccer players without lifting experience (N = 24, age = 16.82 ± 1.56 years, height = 1.64 ± 0.55 cm, body mass = 58.35 ± 6.28 kg). Players were randomized into three groups: A back squat group (SQG; N = 8), hip thrust group (HTG; N = 8), and control group (CG; N = 8). Participants in the HTG and SQG joined a progressive resistance training program twice per week for 7 weeks with either HT or SQ exercises. A countermovement jump, 10-20 m sprint, T-test, and barbell velocity during HTs and SQs (with the load that represents ~60 and ~80% RM) were measured before and after the intervention. The HTG showed greater improvements in the 10-m sprint (d = 0.7), 20-m sprint (d = 0.46), T-test (d = 0.36), and barbell velocity at 80% repetition maximal (RM) (d = 0.53) and 60% RM (d = 1.02) during hip thrusts, while the SQG showed higher barbell velocity at 80% RM (d = −0.7) during back squats. These results may be useful for strength and conditioning coaches working with adolescent female soccer athletes, since both strengthening exercises improved performance in different ways due to the nature of the exercise.
... Despite training and testing to a parallel depth in the squat, the 908 knee angle was chosen to account for the challenges associated with RFD measurements in dynamic, multijoint exercises. Importantly, deep squats have previously been shown to elicit improvements in the 908 SJ (19). Hands were kept at the hip throughout the movement. ...
The aim of this study was to assess the short-term effects of maximal strength training (MST) as an accessory to grappling training on strength performance in competitive Brazilian jiu-jitsu (BJJ) athletes. Fourteen male BJJ athletes underwent measurements of 1 repetition maximum (1RM) in the squat and bench press, rate of force development (RFD) and peak force (PF) in the squat jump, countermovement jump (CMJ) height, and muscular endurance in pull-ups, sit-ups, and push-ups. After baseline measurements, subjects were randomly allocated to either an MST group or control group (CON). The MST intervention consisted of 4 × 4 repetitions at ≥ 85% of 1RM in the squat and bench press, and 4 sets of pull-ups to failure, performed 3× per week. Both groups were instructed to maintain their BJJ training and avoid additional strength training. Maximal strength training improved 1RM in the squat and bench press by 15 ± 9% (p = 0.02) and 11 ± 3% (p = 0.03), respectively, and CMJ height by 9 ± 7% (p = 0.04). Muscular endurance performance increased by 33 ± 33% in pull-ups (p = 0.03), 32 ± 12% in push-ups (p = 0.03), and 13 ± 13% in sit-ups (p = 0.03). Increases in RFD (35 ± 55%, p = 0.13) and PF (8 ± 9%, p = 0.09) did not reach significance. No improvements were apparent from BJJ training alone (p > 0.05). These findings suggest that MST is a potent approach to rapid improvements in maximal strength, power, and muscular endurance in active grapplers.
... The number of repetitions per set decreased from 10 to 4 between the first and last week of training. The weight was chosen to assure muscular failure in the last 2 repetitions of the targeted repetition range while maintaining a proper lifting technique as recommended previously (18). The weight was increased by 2.5 kg for the next set when the athletes reached the upper limit of the targeted repetition range. ...
Keller, S, Koob, A, Corak, D, von Schöning, V, and Born, DP. How to improve change-of-direction speed in junior team sport athletes-Horizontal, vertical, maximal, or explosive strength training? J Strength Cond Res XX(X): 000-000, 2018-The purpose of the study was to compare the effects of 4 different training methods on change-of-direction (COD) speed in junior team sport athletes. Specifically, we investigated whether horizontal load training incorporating lateral acceleration and deceleration would induce superior performance adaptations with respect to COD speed, compared with common vertically oriented maximal strength (squats and deadlifts), explosive strength (power clean and high pull), and vertical jumping exercises. Male U15 team sport athletes (n = 45) were assigned to 1 of 4 groups and performed 2 intervention training sessions per week for 4 weeks, in addition to their usual sport-specific training. Before and after the training period, COD speed, countermovement and drop jump heights, 1-legged lateral jump, and standing long jump performance were assessed. All 4 training groups improved COD speed (p ≤ 0.01, effect size [ES] ≥1.35). Countermovement and 1-legged lateral jump performance improved with the horizontal load (p < 0.01, ES = 0.81 and p < 0.01, ES = 1.36), maximal (p = 0.01, ES = 0.56 and p < 0.01, ES = 1.14), and explosive strength training (p < 0.01, ES = 0.95 and p < 0.01, ES = 1.60, respectively). The standing long jump improved with the maximal (p < 0.01, ES = 1.14) and explosive strength training (p < 0.01, ES = 0.60). In conclusion, all 4 training methods improved the COD speed in junior U15 team sport athletes. These findings emphasize the importance of well-developed lower-body strength and power, which contribute to fast COD speed. From a practical perspective, conditioning programs for junior athletes can incorporate horizontally and vertically oriented exercises with similar effectiveness on COD speed.
... However, the degree of transfer from overloading PROM to FROM exercises appears to be limited, with most studies showing that FROM training exercises are superior for developing FROM strength. 20,40,49 Therefore, incorporating PROM exercises, even when higher relative intensities are used, is unlikely to increase FROM strength to the same degree as if FROM exercises were prioritised. From this perspective, viewing PROM as an advanced strategy for enhancing performance during conventional exercises is limited. ...
The development of maximal strength is a fundamental goal in order to optimise athletic performance. As both morphological and neurological adaptations support the development of maximal strength, practitioners may seek to increase either muscle hypertrophy or intra- and intermuscular coordination in order to create greater force development capacity. Although beginner athletes can achieve this with basic training methods, intermediate and advanced athletes may require greater variation in order to induce the necessary adaptations.
Variation can be created in a training session by prescribing novel loading methods. Part 1 of this series discussed the evidence for accumulation methods, where drop sets, forced repetitions and pre-exhaustion techniques can be used to increase training density, when compared to volume-matched traditional loading schemes. Part 2 will discuss the
evidence for intensification methods, focusing on selected advanced strategies and how they can facilitate higher training intensities, without increasing repetitions. These methods will be viewed from the perspective of increasing muscle hypertrophy and maximal strength.
... En este sentido, sería de gran interés conocer si la producción de fuerza en ejercicios como el press de banca y la sentadilla tienen una relación estrecha con la velocidad de ejecución de las técnicas de puño y pierna más representativos del karate pues, de ser así, podrían proponerse programas de entrenamiento de fuerza con cargas óptimas para mejorar su nivel de rendimiento. En concreto, variables como la rate of force development (RFD), indicador que representa la máxima producción de fuerza en la unidad de tiempo (Blazevich, 2012;Hartmann et al., 2012;Lamas et al., 2012), es decir, la fuerza explosiva máxima, no ha sido investigada en karatecas, y su estudio podría ser clave tanto para detectar talentos como para entender la capacidad de producir fuerza en karatecas de distintos niveles competitivos. ...
Introduction/Aims: Karate is a sport with a high requirement of explosive strength. This communication has two objectives: (1) to describe the explosive strength and the head-on kicking speed of high level karateka, and (2) to know the degree of covariation between these variables.
Method: Participants were 13 Spanish male high level karateka, Shito-ryu style, and kata specialty. This study follows a descriptive correlational design. Variables: upper-body explosive strength obtained using a seated medicine-ball throw test (1), lower-body explosive strength inferred by CMJ vertical jump (2) and kicking speed with Mae-Geri technique (3). Instrumental: an infrared platform (OptoJump, Microgate), a high speed camera(Casio ExFC100), and the video analysis software Kinovea.
Results: The average distance reached in the seated 4kg-medicine ball throw was 4.12 ± 0.51 m, the average CMJ flight time was 630 ± 32 ms, and the average kicking speed was 5.52 ± 0.53 m * s-1 and 5.44 ± 0.39 m * s-1, dominant and non-dominant leg respectively. Despite our small sample size, all correlations were significant with a confidence level of 95% (p <0.05). Correlation were between r=0.55 and r=0.78.
Conclusion: The vertical jump has a statistically significant relationship with the kicking speed, a major variable in karate. In addition, the vertical jump has a high correlation with the medicine ball throw, showing explosive strength balance in this type of athletes. This information can be important when planning training with simple and low cost tests.
References: 1. Gillespie, J., & Keenum, S (1987). A validity and reliability analysis of the seated shot put as a test of power. Journal of Human Movement Studies. 97-105. 2. Ravier, G., Grappe, F., & Rouillon, D. (2004). Application of force-velocity cycle ergometer test and vertical jump test in functional assessment of karate competitor. Journal Sports Medicine Physical Fitness. 349-355. 3. Sforza, C., Turci, M., Grassi, G. P., Shirai, Y. F., Pizzini, G., & Ferrario, V. F. (2002). Repeatability of mae-geri-keage in traditional karate: a three-dimensional analysis with black-belt karateka. Perceptual and Motor Skills. 433-444.
Background: Range of motion (ROM) during resistance training is of growing interest and is potentially used to elicit differing adaptations (e.g. muscle hypertrophy and muscular strength and power). To date, attempts at synthesising the data on ROM during resistance training have primarily focused on muscle hypertrophy in the lower body.
Objective: Our aim was to meta-analyse and systematically review the effects of ROM on a variety of outcomes including hypertrophy, strength, sport, power and body-fat type outcomes. Following pre-registration and consistent with PRISMA guidelines, a systematic review of PubMed and SportsDISCUS was performed. Data was extracted and a Bayesian multi-level meta-analysis was performed. A range of exploratory sub-group and moderator analyses were performed.
Results: The main model revealed a trivial SMD (0.12; 95% CI: –0.02, 0.26) in favour of full ROM compared to partial ROM. When grouped by outcome, SMDs all favoured full ROM, but SMDs were trivial to small (all between 0.05 to 0.2). Sub-group analyses suggested there may be a muscle hypertrophy benefit to partial ROM training at long muscle lengths compared to using a full ROM (–0.28; 95% CI: –0.81, 0.16). Analysis also suggested the existence of a specificity aspect to ROM, such that training in the ROM being tested as an outcome resulted in greater strength adaptations. No clear differences were found between upper- and lower-body adaptations when ROM was manipulated.
Conclusions: Overall, our results suggest that using a full or long ROM may enhance results for most outcomes (strength, speed, power, muscle size, and body composition). Differences in adaptations are trivial to small. As such, partial ROM resistance training might present an efficacious alternative for variation and personal preference, or where injury prevents full-ROM resistance training.
Measuring maximal strength (MSt) is a very common performance diagnoses, especially in elite and competitive sports. The most popular procedure in test batteries is to test the one repetition maximum (1RM). Since testing maximum dynamic strength is very time consuming, it often suggested to use isometric testing conditions instead. This suggestion is based on the assumption that the high Pearson correlation coefficients of r = 0.7 between isometric and dynamic conditions indicate that both tests would provide similar measures of MSt. However, calculating r provides information about the relationship between two parameters, but does not provide any statement about the agreement or concordance of two testing procedures. Hence, to assess replaceability, the concordance correlation coefficient (rhoc) and the Bland-Altman analysis including the mean absolute error (MAE) and the mean absolute percentage error (MAPE) seem to be more appropriate. Therefore, an exemplary model based on r=0.55 showed rhoc = 0.53, A MAE of 413.58N and a MAPE = 23.6% with a range of -1000 – 800N within 95% Confidence interval (95%CI), while r=0.7 and 0.92 showed rhoc =0.68 with a MAE = 304.51N/MAPE = 17.4% with a range of -750N – 600N within a 95% CI and rhoc =0.9 with a MAE = 139.99/MAPE =7.1% with a range of -200-450N within a 95% CI, respectively. This model illustrates the limited validity of correlation coefficients to evaluate the replaceability of two testing procedures. Interpretation and classification of rhoc, MAE and MAPE seem to depend on expected changes of the measured parameter. A MAPE of about 17% between two testing procedures can be assumed to be intolerably high.
BACKGROUND: Although squat depth determines the weight that can be lifted while squatting, it is unclear whether the One-repetition maximum (1RM) at one squat depth can be used to estimate the 1RM at another squat depth. OBJECTIVE: To determine the correlations between 1RM weights at different back squat depths (BSQs) in frequently trained male collegiate athletes. METHODS: This cross-sectional study included 26 male collegiate athletes. Body composition, lower extremity length, and 1RM of BSQ were measured. 1RM of BSQ was measured at three positions (quarter, half and parallel positions), defined as 45 degrees of knee flexion (quarter, Q-SQ), 90 degrees of knee flexion (half, H-SQ), and femur parallel to the ground (parallel, P-SQ), respectively. All testing was conducted by a certified strength and conditioning specialist. Pearson’s correlation analysis and Spearman’s rank correlation were used to examine the correlation between 1RM at each squat depth. RESULTS: There was a significant correlation between 1RM in the H-SQ and P-SQ positions (p< 0.001, r= 0.725, R2= 0.526, y= 1.0728x+ 24.641), but no significant correlation between 1RM of Q-SQ and P-SQ, and 1RM of Q-SQ and H-SQ. There were significant correlations between the 1RM of Q-SQ and height (p= 0.001, r= 0.594), and with the length of the lower extremities (p= 0.002, r= 0.586). CONCLUSIONS: Mutual estimation of the 1RM of H-SQ or P-SQ from the 1RM of the other squat position is possible. Estimation of the 1RM of Q-SQ from the 1RM of H-SQ or P-SQ is, however, difficult, and must be measured separately. Future studies should be conducted with larger sample sizes, in athletes of various sports, and in females.
Background: Range of motion (ROM) during resistance training is of growing interest and is potentially used to elicit differing adaptations (e.g. muscle hypertrophy and muscular strength and power). To date, attempts at synthesising the data on ROM during resistance training have primarily focused on muscle hypertrophy in the lower body. Objective: Our aim was to meta-analyse and systematically review the effects of ROM on a variety of outcomes including hypertrophy, strength, sport, power and body-fat type outcomes. Following pre-registration and consistent with PRISMA guidelines, a systematic review of PubMed and SportsDISCUS was performed. Data was extracted and a Bayesian multi-level meta-analysis was performed. A range of exploratory subgroup and moderator analyses were performed. Results: The main model revealed a trivial SMD (0.13; 95% CI: −0.01, 0.27) in favour of full ROM compared to partial ROM. When grouped by outcome, SMDs all favoured full ROM, but SMDs were trivial to small (all between 0.05 to 0.2). Subgroup analyses suggested there may be a muscle hypertrophy benefit to partial ROM training at long muscle lengths compared to using a full ROM (SMD=−0.28, 95% CI: −0.81, 0.16). Analysis also suggested the existence of a specificity aspect to ROM, such that training in the ROM being tested as an outcome resulted in greater strength adaptations. No clear differences were found between upper-and lower-body adaptations when ROM was manipulated. Conclusions: Overall, our results suggest that using a full or long ROM may enhance results for most outcomes (strength, speed, power, muscle size, and body composition). Differences in adaptations are trivial to small. As such, partial ROM resistance training might present an efficacious alternative for variation and personal preference, or where injury prevents full-ROM resistance training.
This study examined the test re-test, intrarater and interrater reliability of joint kinematics from the coach's Eye smartphone application. Twenty-two males completed a 1-repetition maximum (1-rM) assessment followed by 2 identical sessions using 5 incremental loads (20, 40, 60, 80, 90% 1-rM). Peak flexion angles at the hip, knee, and ankle joints were assessed using 1 experienced practitioner and 1 inexperienced practitioner. the acceptable reliability thresholds were defined as intraclass correlation coefficient (Icc) r > 0.70 and coefficient of variation cv ≤ 10%. the test re-test reliability of peak hip and knee flexion were reliable across 20-90% 1-rM (r > 0.64; cv < 4.2%), whereas peak ankle flexion was not reliable at any loaded condition (r > 0.70; cv < 20.4%). no significant differences were detected between trials (p > 0.11). the intrarater reliability was near perfect (r > 0.90) except for peak ankle flexion (r > 0.85). the interrater reliability was nearly perfect (r > 0.91) except for hip flexion at 80% 1-rM and ankle flexion at 20% (r > 0.77). concludingly, the coach's Eye application can produce repeatable assessments of joint kinematics using either a single examiner or 2 examiners, regardless of experience level. the coach's Eye can accurately monitor squat depth.
Squatting has received considerable attention in sports and is commonly utilized in daily activities. Knowledge of the squatting biomechanics in terms of its speed and depth may enhance exercise selection when targeting for sport-specific performance improvement and injury avoidance. Nonetheless, these perspectives have not been consistently reported. Hence, this preliminary study intends to quantify the kinematics, kinetics, and energetics in squat with different depths and speeds among healthy young adults with different physical activity levels; i.e., between active and sedentary groups. Twenty participants were administered to squat at varying depths (deep, normal, and half) and speeds (fast, normal, and slow). Motion-capture system and force plates were employed to acquire motion trajectories and ground reaction force. Joint moment was obtained via inverse dynamics, while power was derived as a product of moment and angular velocity. Higher speeds and deeper squats greatly influence higher joint moments and powers at the hip ([Formula: see text]) and knee ([Formula: see text]) than ankle, signifying these joints as the prime movers with knee as the predominant contributor. These preliminary findings show that the knee-strategy and hip-strategy were employed in compensating speed and depth manipulations during squatting. In certain contexts, appreciating these findings may provide clinically relevant implications, from the performance and injury avoidance viewpoint, which will ameliorate the physical activity level of practitioners.
Le concept des achats responsables occupe, avec les nouvelles réglementations, une place centrale dans la mise en œuvre des stratégies responsables de l’entreprise. Toutefois, vingt ans de recherches n’ont pas permis de proposer une mesure globale de sa performance. L’impact des actions responsables aux achats sur la performance financière reste donc à explorer. Ce travail met en perspective dans un même modèle les deux performances, et étudie le rôle médiateur de trois ressources intangibles (le capital humain, l’innovation et la réputation) entre les ressources tangibles de l’entreprise et la performance des achats responsables. Les résultats de ce travail – suite à l’analyse de 1918 observations, dans 18 pays européens, de 2011 à 2017, issues des principales bases de données (Vigeo Eiris, Institute Réputation, Infinancials, et Thomson Reuters) - confirment l’hypothèse selon laquelle les ressources – notamment le capital humain – contribuent à améliorer la performance des achats responsables, qui impacte à son tour la performance financière de l’entreprise.
Background:
The aim of this study was to classify Olympic medalists and non-medalists among national bobsled and skeleton athletes and determine the physical fitness differences between the two groups.
Methods:
Five bobsleigh and skeleton athletes who won gold and silver medals in the 2018 Pyeongchang Winter Olympics and 11 national bobsled and skeleton team athletes were recruited. The participants were assessed for physiological parameters such as body composition, anthropometry, physical fitness, isokinetic strength, and maximum strength.
Results:
Physical fitness factors back strength (t=2.571, P<0.05), squat ability (t=3.061, P<0.01), and left and right leg curls (t=4.578, P<0.001; t=4.719, P<0.001, respectively) were significantly different between the groups. The original value of the primary discriminant analysis was 1.868 and the canonical correlation was 0.807. The average value of the discriminant function of the medalists was 1.896, while the of the non-medalists was -0.862, indicating that the two groups were completely different.
Conclusions:
Medalists have higher squat abilities, abdominal strength, and leg curl strength than non-medalists, particular regarding hamstring strength. Currently, in most sports events, athletes undergo physical training to improve performance; however, training programs that reflect the characteristics of the sport and the physical characteristics of excellent athletes are still insufficient.
Summary of the doctoral thesis Introduction: In many sports, strength is considered an important basis for performance. One factor affecting strength is muscle mass. Therefore, it may be necessary to increase muscle mass in athletes through resistance training. However, the most effective strategy to gain muscle mass has not yet been clearly identified. Many methods used in practice are based on anecdotal evidence rather than empirical data. For this reason, different approaches to hypertrophy training were examined in this thesis based on three studies. The methods and most important results of these studies are summarized in the following. Methods: In the first study, adolescent American football players completed a 12-week resistance training program with three total-body training sessions per week using either Block Periodization (BLOCK) or Daily Undulating Periodization (DUP). The aim was to investigate the effects of the different periodization strategies on muscle mass and athletic performance. The second study assessed the impact of a three-week detraining period (DTR) on anthropometric measures and sport performance. In a third study, highly trained male subjects completed a six-week low-intensity calf resistance training intervention either without (noBFR) or with blood flow restriction (BFR). Before and after the intervention, 1-RM calf raise, calf volume, muscle thickness of the gastrocnemius, and leg stiffness were recorded. Results: At the end of the first intervention, both periodization groups showed significantly higher muscle mass and thickness, as well as athletic performance without differences between groups. Following DTR, fat mass increased significantly, and fat-free mass was reduced. All other measures were unchanged after DTR. Both BFR and NoBFR training resulted in significant increases in 1-RM and muscle thickness without differences between groups. Calf volume and leg stiffness remained unchanged in both conditions. Conclusions: In adolescent American football players, the structure of periodization does not appear to have any effect on muscle growth. Furthermore, a three weeks DTR does not result in negative effects. Both results provide new insights that can be helpful when creating training programs as well as for planning training-free periods. The currently frequently investigated BFR training does not show higher effects on muscle growth of the lower extremities than conventional low-intensity resistance training.
Background
Muscular rate of force development (RFD) is positively influenced by resistance training. However, the effects of movement patterns and velocities of training exercises are unknown.
Objectives
To determine the effects of velocity, the intent for fast force production, and movement pattern of training exercises on the improvement in isometric RFD from chronic resistance training.
Methods
A systematic search of electronic databases was conducted to 18 September, 2018. Meta-regression and meta-analytic methods were used to compute standardized mean differences (SMD ± 95% confidence intervals) to examine effects of movement pattern similarity (between training and test exercises; specific vs. non-specific) and movement speed (fast vs. slow vs. slow with intent for fast force production) for RFD calculated within different time intervals.
Results
The search yielded 1443 articles, of which 54 met the inclusion criteria (59 intervention groups). Resistance training increased RFD measured to both early (e.g., 50 ms; standardized mean difference [95% CI] 0.58 [0.40, 0.75]) and later (e.g., 200 ms; 0.39 [0.25, 0.52]) times from contraction onset, as well as maximum RFD (RFDmax; 0.35 [0.21, 0.48]). However, sufficient data for sub-analyses were only available for RFDmax. Significant increases relative to control groups were observed after training with high-speed (0.54 [0.05, 1.03]), slow-speed with intent for fast force production (0.41 [0.20, 0.63), and movement pattern-specific (0.38 [0.17, 0.59]) exercises only. No clear effect was observed for slow-speed without intent for fast force production (0.21 [0.00, 0.42], p = 0.05) or non-movement-specific (0.27 [− 0.32, 0.85], p = 0.37) exercises. Meta-regression did not reveal a significant difference between sexes (p = 0.09); however, a negative trend was found in women (− 0.57 [− 1.51, 0.37], p = 0.23), while a favorable effect was found in men (0.40 [0.22, 0.58], p < 0.001). Study duration did not statistically influence the meta-analytic results, although the greatest RFD increases tended to occur within the first weeks of the commencement of training.
Conclusions
Resistance training can evoke significant increases in RFD. For maximum (peak) RFD, the use of faster movement speeds, the intention to produce rapid force irrespective of actual movement speed, and similarity between training and testing movement patterns evoke the greatest improvements. In contrast to expectation, current evidence indicates a between-sex difference in response to training; however, a lack of data in women prevents robust analysis, and this should be a target of future research. Of interest from a training program design perspective was that RFD improvements were greatest within the first weeks of training, with less ongoing improvement (or a reduction in RFD) with longer training, particularly when training velocity was slow or there was a lack of intent for fast force production.
Mortality rate increases exponentially with people’s age. They gather age-related diseases and become ‘frail’, i.e. increasingly vulnerable to various stressors. The gold standard to evaluate the severity of upper limb motor symptoms is to use the UPDRS-part III (motor examination) yet it is proven that simple tests of manual dexterity can identify persons at high risk for neurodegenerative diseases. The aim of this study is to evaluate a novel, objective, observer-independent and assistance-independent tablet device-based method which could be helpful in the upper limb function diagnostics designed for telemedicine technology and frailty assessment. The test employs a tablet and a fixed-height obstacle. The patient is required to move his/her hand above the obstacle and touch the round fields displayed on the tablet. The test is performed for 30 s, as fast as possible, using pointing finger of the dominating hand. Several parameters are registered using the tablet. In the study, the test is evaluated in the group inpatients of geriatric hospital separated into Frail (14 patients) and Control (14 patients) groups. The patients in the Control group are featuring (Mann-Whitney U-test, p-value < 0.05) more correct touches (23.4±8.2 vs. 17.1±12.4) than the members of the Frail group. The reaction time and mean time between touches in Control group is shorter than in the Frail group (respectively Mann-Whitney U-test and Student’s t-test; p-value < 0.05).
Males (n = 29) and females (n = 34) performed vertical jumps. Jump height was estimated from force platform data using five numerical methods and compared using intraclass correlation (ρ), and linear and rank regression standard error of estimate (SEE). Take-off velocity plus center of mass height at take-off and mechanical work methods were identical (ρ = 1.000) with small linear (SEE < 0.0001 cm) and rank order (SEE = 0) error. Integrating acceleration to displacement was nearly identical (ρ > 0.999), with small linear (SEE = 0.1 cm) and rank order (SEE < 1) errors compared to the above methods. Take-off velocity (ρ = 0.517) and flight time (ρ = 0.573) estimates were less than all other methods and had large linear (SEE ≥ 2.1 cm) and rank order (SEE > 4) errors. Take-off velocity and flight time methods should be avoided due to systematic and random error.
The aim of this study was to create a mathematical model of the RRR anthropomorphic mechanism for a 2D biomechanical analysis of a deep squat and related forms of movement. The segment stick model is desig ned to diagnose the movement with sagittal plan symmetry. Based on the input data from kinematic and dynamome tric analysis, and from the anthropometric data of the monitored person, it is possible to estimate the resulting momentum of the forces acting on the main joints of the lower body. The technology may be applied in analysing deep squats, studying the dynamics of vertical reflection as well as in the biomechanical analysis of related forms of movement (e.g. standing-up, squatting with a dumbbell, skiing in downhill posture, etc.). The derived motion equations may be used to analyse the dynamics of the movement of anthropomorphic or mechatronic systems with the same geometry.
1 Finland HÄKKINEN K., KOMI P.V. & TESCH P.A. Effect of ccmbined concentric ard eccentric strength training and detraining on force-time, muscle fiber-and metabolic characteristics of leg extensor muscles. Scand. J ,Sports Sci. 3 (2): 50-58, 1981. Prog¡essive strength training of combined concentric and eccentric contractions were performed three times a week for 16 weeks by 14 males {20-30 yrs of age) accustomed to weight training. The training peeriod was iollowed bv 8 weeks of detraining. The training program consisted mainly of dynamic exeicises for the ieg-extensovs with loads of 80 to 120 of one maximum repetition The training caused significant improvements in-maximal force (p < 0.001) and various force-time (p (0.05-4.01) para¡àeters. Du¡ing thg I'ast trarning àionìh tbe inãrease in force was gireatly tri¡nited' and there was ¿ decrease in th,e force-time parameters. The marked improvements in mwcle strength were accompanied by ccnsiderable intemål qdaptatioos ,Ín-ttre tnaCned muscle, as Judged from l¡rcreases (p < 0-001) ,iqr. the fibet ãeas ôt tËe Ïast fi¡¡itch (FT) and slow twitch (ST) fibers. Durlng early conditioning improvement i! the qqgs! jump w,as related to tl.e relãtive hypertrop]ty of tr1l ii¡eis fo <0.01). No sier¡j-Êi,cå,r¡t ct¡anges ,in tJre er¡zyme aittv¡tiês oi mÍoki¡¡ase-a¡¡d creatine kirmse were found as a result of-tra¡rrir}g, but i,ndividt¡al charrges in my-o-kinase activity $/ere related to the relative. hypertrop'hy of FT fibers-(p ç 0.05) and Improvernent i+ the squat jump (p < O.Of)-during early conditiontuag. All the ada,p-iatlo:ns'-incilcating musõle hypertrophy occurred. prtm@lv during the last two training mo¡rths. Decreases (p (0.001) in maxirnal force during the detrairring were accompâ-nied bv a sisrificår¡t rediuction in the fi¡b,er areas of ttle fC tp < 0.01) and ST (p < 0.05) tvpes end by a change in bödy-antliropometry.-A periodiè-and partial usage. of àccentr-ic contráctions,-together with conèentric training' is suggested to be effectiùe in training for-maximal force and äso for force-time eharacteristics. In training of longer durations the specific effects of strength trainlng are-obviot¡s and explaiñable by adaptatlons in the trained muscle. Keg tenns: erìzJûne actlvities, muscle mechanics, muscle metabollsn, muscle streng:th.
Squat constitutes one of the most popular exercises to strengthen the muscles of the lower limbs. It is considered one of the most widely spread exercises for muscle sport training and is part of the competition movements comprised within olympic weight-lifting. In physical rehabilitation, squats are used for muscular recovery after different injuries of the lower limbs, especially the knee. In previous anterior cruciate ligament injuries, the mini-squats are generally used, in a knee flexion motion range from 0° to 50° because in this range the shear forces, the tibiofemoral and patellofemoral compression forces decrease related to greater flexion angles. The aim of this work is to make a comparative bidimensional study of the kinematic and dynamic variables of the excecution of the parallel squat exercise with the front and back bar. It is observed in the knee a better development of energy with the front bar, allowing a better muscular exercise with the same load. The mean power absorbed by the hip with the back bar is considerably greater, associated to the speed of the gesture.
The purpose of the present study was to investigate the effect of supplemental heavy strength training on muscle thickness and determinants of performance in well-trained Nordic Combined athletes. Seventeen well-trained Nordic Combined athletes were assigned to either usual training supplemented with heavy strength training (STR; n = 8) or to usual training without heavy strength training (CON; n = 9). The strength training performed by STR consisted of one lower-body exercise and two upper-body exercises [3-5 repetition maximum (RM) sets of 3-8 repetitions], which were performed twice a week for 12 weeks. Architectural changes in m. vastus lateralis, 1RM in squat and seated pull-down, squat jump (SJ) height, maximal oxygen consumption (VO(2max)), work economy during submaximal treadmill skate rollerskiing, and performance in a 7.5-km rollerski time trial were measured before and after the intervention. STR increased 1RM in squat and seated pull-down, muscle thickness, and SJ performance more than CON (p < 0.05). There was no difference between groups in change in work economy. The two groups showed no changes in total body mass, VO(2max), or time-trial performance. In conclusion, 12 weeks of supplemental strength training improved determinants of performance in Nordic Combined by improving the athletes' strength and vertical jump ability without increasing total body mass or compromising the development of VO(2max).
The purpose of this article was to investigate the relation between anthropometric and physiological variables to linear bat swing velocity (BV) of 2 groups of high-school baseball players before and after completing a 12-week periodized resistance exercise program. Participants were randomly assigned to 1 of 2 training groups using a stratified sampling technique. Group 1 (n = 24) and group 2 (n = 25) both performed a stepwise periodized resistance exercise program and took 100 swings a day, 3 d·wk-1, for 12 weeks with their normal game bat. Group 2 performed additional rotational and full-body medicine ball exercises 3 d·wk-1 for 12 weeks. Fourteen variables were measured or calculated before and after 12 weeks of training. Anthropometric and physiological variables tested were height, body mass, percent body fat, lean body mass (LBM), dominant torso rotational strength (DTRS) and nondominant torso rotational strength (NDTRS), sequential hip-torso-arm rotational strength measured by a medicine ball hitter's throw (MBHT), estimated 1 repetition maximum parallel squat (PS) and bench press (BP), vertical jump (VJ), estimated peak power, angular hip velocity (AHV), and angular shoulder velocity (ASV). The baseball-specific skill of linear BV was also measured. Statistical analysis indicated a significant moderately high positive relationship (p ≤ 0.05) between prelinear BV and pre-NDTRS for group 1, pre-LBM, DTRS, NDTRS, peak power, and ASV for group 2; moderate positive relationship between prelinear BV and preheight, LBM, DTRS, peak power, BP, PS, and ASV for group 1, preheight, body mass, MBHT, BP, and PS for group 2. Significantly high positive relationships were indicated between postlinear BV and post-NDTRS for group 1, post-DTRS and NDTRS for group 2; moderately high positive relationships between postlinear BV and post-LBM, DTRS, peak power, BP, and PS for group 1, postheight, LBM, VJ, peak power for group 2; moderate positive relationships between postlinear BV and postheight, body mass, MBHT, and VJ for group 1, postbody mass, MBHT, BP, PS, and ASV for group 2. Significantly low positive relationships were indicated between prelinear BV and prebody mass, MBHT, and VJ for group 1, pre-VJ and AHV for group 2; postlinear BV and post-AHV for group 2. These data show that significant relationships do exist between height, body mass, LBM, rotational power, rotational strength, lower body power, upper and lower body strength, AHV, and ASV to linear BV of high-school baseball players. Strength coaches may want to consider using this information when designing a resistance training program for high-school baseball players. Those recruiting or scouting baseball players may want to use this information to further develop ways of identifying talented players. However, one should be cautious when interpreting this information when designing strength training programs for high-school baseball players to increase linear BV.
Finite element analysis results will show significant differences if the model used is performed under various material properties, geometries, loading modes or other conditions. This study adopted an FE model, taking into account the possible asymmetry inherently existing in the spine with respect to the sagittal plane, with a more geometrically realistic outline to analyze and compare the biomechanical behaviour of the lumbar spine with regard to the facet force and intradiscal pressure, which are associated with low back pain symptoms and other spinal disorders. Dealing carefully with the contact surfaces of the facet joints at various levels of the lumbar spine can potentially help us further ascertain physiological behaviour concerning the frictional effects of facet joints under separate loadings or the responses to the compressive loads in the discs.
A lumbar spine model was constructed from processes including smoothing the bony outline of each scan image, stacking the boundary lines into a smooth surface model, and subsequent further processing in order to conform with the purpose of effective finite element analysis performance. For simplicity, most spinal components were modelled as isotropic and linear materials with the exception of spinal ligaments (bilinear). The contact behaviour of the facet joints and changes of the intradiscal pressure with different postures were analyzed.
The results revealed that asymmetric responses of the facet joint forces exist in various postures and that such effect is amplified with larger loadings. In axial rotation, the facet joint forces were relatively larger in the contralateral facet joints than in the ipsilateral ones at the same level. Although the effect of the preloads on facet joint forces was not apparent, intradiscal pressure did increase with preload, and its magnitude increased more markedly in flexion than in extension and axial rotation.
Disc pressures showed a significant increase with preload and changed more noticeably in flexion than in extension or in axial rotation. Compared with the applied preloads, the postures played a more important role, especially in axial rotation; the facet joint forces were increased in the contralateral facet joints as compared to the ipsilateral ones at the same level of the lumbar spine.
The squat is one of the most frequently used exercises in the field of strength and conditioning. Considering the complexity of the exercise and the many variables related to performance, understanding squat biomechanics is of great importance for both achieving optimal muscular development as well as reducing the prospect of a training-related injury. Therefore, the purpose of this article is 2-fold: first, to examine kinematics and kinetics of the dynamic squat with respect to the ankle, knee, hip and spinal joints and, second, to provide recommendations based on these biomechanical factors for optimizing exercise performance.
Careful review of published evidence has led to the postulate that the degree of lumbar lordosis may possibly influence the development and progression of spinal osteoarthritis, just as misalignment does in other joints. Spinal degeneration can ensue from the asymmetrical distribution of loads. The resultant lesions lead to a domino- like breakdown of the normal morphology, degenerative instability and deviation from the correct configuration. The aim of this study is to investigate whether a relationship exists between the sagittal alignment of the lumbar spine, as it is expressed by lordosis, and the presence of radiographic osteoarthritis.
112 female subjects, aged 40-72 years, were examined in the Outpatients Department of the Orthopedics' Clinic, University Hospital of Heraklion, Crete. Lumbar radiographs were examined on two separate occasions, independently, by two of the authors for the presence of osteoarthritis. Lordosis was measured from the top of L1 to the bottom of L5 as well as from the top of L1 to the top of S1. Furthermore, the angle between the bottom of L5 to the top of S1 was also measured.
49 women were diagnosed with radiographic osteoarthritis of the lumbar spine, while 63 women had no evidence of osteoarthritis and served as controls. The two groups were matched for age and body build, as it is expressed by BMI. No statistically significant differences were found in the lordotic angles between the two groups
There is no difference in lordosis between those affected with lumbar spine osteoarthritis and those who are disease free. It appears that osteoarthritis is not associated with the degree of lumbar lordosis.
The aim of the present study was to investigate the effects of voluntary maximal leg strength training on peak power output (Wpeak), vertical jump performance, and field performances in junior soccer players. Twenty-two male soccer players participated in this investigation and were divided into 2 groups: A resistance training group (RTG; age 17 +/- 0.3 years) and a control group (CG; age 17 +/- 0.5 years). Before and after the training sessions (twice a week for 2 months), Wpeak was determined by means of a cycling force-velocity test. Squat jump (SJ), countermovement jump (CMJ), and 5-jump test (5-JT) performances were assessed. Kinematics analyses were made using a video camera during a 40-m sprint running test and the following running velocities were calculated: The first step after the start (V(first step)), the first 5 m (V(first 5 meters)), and between the 35 m and 40 m (V(max)). Back half squat exercises were performed to determine 1-repetition maximum (1-RM). Leg and thigh muscle volume and mean thigh cross-sectional area (CSA) were assessed by anthropometry. The resistance training group showed improvement in Wpeak (p < 0.05), jump performances (SJ, p < 0.05 and 5-JT, p < 0.001), 1-RM (p < 0.001) and all sprint running calculated velocities (p < 0.05 for both V(first step) and V(first 5 meters), p < 0.01 for V(max)). Both typical force-velocity relationships and mechanical parabolic curves between power and velocity increased after the strength training program. Leg and thigh muscle volume and CSA of RTG remained unchanged after strength training. Back half squat exercises, including adapted heavy loads and only 2 training sessions per week, improved athletic performance in junior soccer players. These specific dynamic constant external resistance exercises are highly recommended as part of an annual training program for junior soccer players.
The strength and stability of the knee plays an integral role in athletics and activities of daily living. A better understanding of knee joint biomechanics while performing variations of the squat would be useful in rehabilitation and exercise prescription. We quantified and compared tibiofemoral joint kinetics as well as muscle activity while executing front and back squats. Because of the inherent change in the position of the center of mass of the bar between the front and back squat lifts, we hypothesized that the back squat would result in increased loads on the knee joint and that the front squat would result in increased knee extensor and decreased back extensor muscle activity. A crossover study design was used. To assess the net force and torque placed on the knee and muscle activation levels, a combination of video and force data, as well as surface electromyographic data, were collected from 15 healthy trained individuals. The back squat resulted in significantly higher compressive forces and knee extensor moments than the front squat. Shear forces at the knee were small in magnitude, posteriorly directed, and did not vary between the squat variations. Although bar position did not influence muscle activity, muscle activation during the ascending phase was significantly greater than during the descending phase. The front squat was as effective as the back squat in terms of overall muscle recruitment, with significantly less compressive forces and extensor moments. The results suggest that front squats may be advantageous compared with back squats for individuals with knee problems such as meniscus tears, and for long-term joint health.
To investigate the influence of strength training on the electrical and mechanical behaviour of leg extensor muscles during concentric and various stretch-shortening cycles exercises, eleven male subjects went through dynamic heavy resistance strength training with loads of 70 to 120% one maximum repetition three times a week for 24 weeks. The heavy resistance strength training resulted in specific changes in neuromuscular performance. This was demonstrated by the great (p< 0.001) shift of primarily the high force portions of the force velocity curves measured both during squat (SJ) and counter movement jumping (CMJ) conditions. An increase of 30.2% (p<0.001) in maximal strength was noted during the training, while the increases became gradually smaller near the high velocity portions of the curve, where an increase of 7.3% (p<0.05) in the jumping height in SJ and a non-significant increase in the maximal extension velocity with free loads were noted. The increases in positive work phases of force production were accompanied by significant (p<0.05) increases in the neural activation (IEMG) of primarily the vasti medialis and lateralis muscle, while only slight changes were noted in the RF muscle. Only minor and mostly nonsignificant changes were observed during the strength training in the neural activation and force production of the leg extensor muscles in various drop jumps, in which high contraction velocities are utilized. When the training was followed by a 12-week detraining, a great (p<0.001) decrease in maximal strength was observed, while the changes in various parameters of explosive force production were either small (p<0.05) or nonsignificant. The present findings regarding the changes in the electrical and mechanical behaviour of the leg extensor muscles during heavy resistance strength training give additional support to the concept of specificity of training.
Three high-skilled powerlifters performed parallel squats with different burden weights. Using a sagittal plane biomechanical model, the moments of force about the bilateral axes of the lumbo-sacral, hip, knee, and ankle joints were determined. A local biomechanical model of the knee was used in order to calculate the knee joint forces induced. The greatest moments were found in the lumbo-sacral joint. The maximum hip moment was greater than that of the knee moment which was greater than the ankle moment. The knee moment had a flexing direction and reached its maximum at the deepest position of the squat, while the lumbo-sacral and hip moments were found to reach their maxima during the first half second of the ascent. One lift that caused a bilateral quadriceps tendon rupture was stimulated and was found to give a maximum knee flexing moment ranging between 335 Nm and 550 Nm. This moment induced a force in each quadriceps tendon of between 10.9 kN and 18.3 kN at the occasion of rupture.
The ability to maintain strength, speed, endurance and quickness throughout a season is vital to the success of a team. The purpose of this investigation was to examine these factors during the course of college basketball season. Nine members of an NCAA Division I men's basketball team volunteered to be evaluated. Testing was conducted four times over the duration of the season: before a five-week resistance training program (RTP); before preseason practice (PRES); midseason (MS); and within two days after the conclusion of postseason tournaments. There was no RTP during the basketball season. Field tests common to athletic conditioning programs were used to evaluate strength (I RM squat and bench press), speed (27-meter sprint), endurance (2,414- meter run [1.5 miles]), vertical jump and anthropometric measurements. Maximal isometric and dynamic strength also were measured in the subject's dominant leg using an isokinetic dynamometer. Increases (p < 0.05) after the RTP were observed only for the squat and at 1.05 radians per second knee extension and flexion movement of isokinetic testing. At MS a decrease (p < 0.05) was observed in squat and VJ, and slower times (p < 0.05) were observed in 27-meter sprint from the PRES values. Final resting revealed that speed still was slower (p < 0.05) than PRES values, and that peak torque was increased at the 1.05 and 3.14 radians per second knee extension movement. These data suggest that the athlete can maintain most preseason conditioning levels during the course of a college basketball season.
(C) 1991 National Strength and Conditioning Association
This study examined the effects of manipulating volume and intensity on strength and power in experienced male athletes. Subjects (N = 22) were tested for maximum strength in the squat and bench press lifts, vertical jump (VJ), lean body mass (LBM), and neural activation levels (IEMG). They trained 3 days a week for 12 weeks according to a linear periodization model (n = 8), an undulating periodization model (n = 5), or a nonperiodized control model (n = 9). Training volume and relative intensity were equated for all groups. Maximal squat, bench press, and LBM all improved significantly in each group, and changes in maximal strength correlated significantly with changes in LBM. IEMG levels were generally unchanged and did not correlate with changes in strength. The VJ increased significantly through training, but there were no differences between groups. Changes in VJ were not significantly correlated with changes in squat, LBM, or IEMG levels. The results indicate that in short-term training using previously trained subjects, no differences in maximal strength are seen when training volume and relative intensity are equated.
(C) 1994 National Strength and Conditioning Association
While no clear-cut distinction between “muscle training” and “nerve training” can be made, the approach presented has emphasized the muscle during the early preparation (high volume), then emphasized the central nervous system (high intensity and increased technique work) during the later stages of training. The authors’ research and observations, that of other researchers, and the subjective evaluations of athletes and coaches who have tried this method suggest this to be a superior method of strength-power training. This model of training has been compared to various methods of strength-power training including 3 sets of six RM, pyramiding, low repetitions and various sets to exhaustion (1-3). Based on these comparisons the following conclusions were reached: 1. The model produced superior gains in leg and hip strength (1 RM) (10 of 11 studies). 2. The model produced superior gains in leg and hip power (VJ and Lewis formula) in all 11 studies. 3. The model generally produced superior gains in upper body strength (1RM Bench Press). (However, a few studies showed equal gains when compared to 3 × 6 RM and pyramiding over a short term [6–12 weeks]). 4. Positive changes in body composition (% fat and LBM) were greater in those subjects using the training model in most of the 11 studies. This was especially evident after high volume training (sets of 10). 5. Based on cycle ergometry of increasing intensity to exhaustion, the model produced greater gains in short term endurance. This was especially apparent after high volume training (sets of 10). While this method of training is not the final answer, it is based on sound concepts and principles and will provide the coach-athlete with a superior training program.
The effects of different methods of weight training on strength and short-term work capacity are not clearly understood. This study describes the leg and hip maximum strength and endurance responses to two different weight training methods. Ninety healthy college males were divided into two training groups. Group 1 (G1, n = 46) used a "periodized" approach of moving from high-volume, low-intensity to low-volume, high-intensity exercise across the training program (11 weeks). Group 2 (G2, n = 44) used a 3 x 6 RM. Changes in maximum strength were measured with a 1 RM parallel squat. Power capacity was measured by incremental cycle ergometer exercise. A subset of each group (G1 = 17; G2 = 14) was used in the estimation of short-term power capacity. The results show that weight training can significantly (p<.01) increase maximum strength and short-term power capacity (endurance) simultaneously and that the periodized group (G1) produced superior results.
(C) 1988 National Strength and Conditioning Association
This study compared the effects of three preseason training programs on endurance, strength, power, and speed. Subjects were divided into four groups: the endurance (E) group completed a running endurance program 4 days [middle dot] week-1; the strength (S) group trained 3 days [middle dot] week-1; the S+E group combined S and E training programs 5 days [middle dot] week-1; the control (C) group did not train. After 8 weeks, the E and S+E groups had similar gains in endurance running performance, the S group had no change, while the C group showed a decline. No strength gains were noted in the C or E groups, but strength gains were made in the S+E and S groups. Power (vertical jump performance) and speed (20-m sprint time) gains were noted only for the S group. These findings show that training for strength alone results in gains in strength, power, and speed while maintaining endurance. S+E training, while producing gains in endurance and upper body strength, compromises gains in lower body strength and does not improve power or speed.
(C) 1994 National Strength and Conditioning Association
In selecting strength and conditioning exercises for speed-oriented athletes, consideration should be made for the mechanics of the sport, the involvement of the various components of speed, and the nature under which speed is executed.
This study investigated the effects of execution speed on measures of strength, muscular power, and hypertrophy. Eighteen male subjects trained with the half-squat exercise using an 8- to 12-RM load for 7-1/2 weeks. Eight subjects tried to produce fast concentric contractions while 10 subjects emphasized slow controlled movements. Both groups improved significantly in all measures; however, no significant differences were observed between the groups over the training period. Trends based on percentage improvements gave some support for the fast group improving more (68.7%) than the slow group (23.5%) in maximum rate of force development. The slow group improved to a greater extent (31%) that the fast group (12.4%) in absolute isometric strength, whereas the percentage gains in hypertrophy were similar for both groups. It was concluded that strength, speed-strength, and hypertrophy measures can be simultaneously developed significantly in beginning weight trainers. Beginner athletes should consider the possible effects of consciously controlling speed of contraction in weight training.
(C) 1993 National Strength and Conditioning Association