Article

Influence of Squatting Depth on Jumping Performance

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  • German University of Health and Sport
Article

Influence of Squatting Depth on Jumping Performance

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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.

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... 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. ...
Article
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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.
... 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). ...
Article
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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.
... 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. ...
Article
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.
... 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. ...
Article
Full-text available
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.
... 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 ...
... 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. ...
Article
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.
... 3 Sprint coaches have a vast amount of research to choose from in the team sports realm, yet within their own realm it is more difficult for them to select exercises based on the available research. Even fundamental exercise selection can range from regular full range of movement (ROM) squats, 11 variable range of motion squats, 11,13,14 squat jumps, 15 banded squats, 16,17 all of which show performance improvement, yet the specificity for the sport of sprinting is unclear. [18][19][20][21] Research (33) has shown a need to bridge the gap between researchers and practitioners with regard to resistance-based training interventions. 3 Coaches have indicated that they are less likely to look for research about physical training but are happy that sports science is contributing to this area. ...
... One coach used what they termed the 'i squat' along with 'squat jumps', while another coach specifically mentioned using a '¼ squat'. Research by Hartmann et al. 14 on variable range of motion squats questions the necessity to use partial ranges like the ¼ squat, while others are advocates of this method. 13,34 Five of the coaches used parallel or above ROM squats, while one coach promoted the use of full ROM squats to facilitate adequate strength development. ...
... segment of the movement amplitude, there should be no necessity for training the maximal strength over the whole range of motion. While this line of argument is mimicked by the coaches' views below, it is by no means conclusive.Contrary to the above views, Coach #3 had an alternative view point about the ROM of the squat, which is mirrored by the views of Hartmann et al.,14 who's findings contest the concept of superior angle-specific transfer effects. Hartmann et al.'s findings suggest that deep front and back squats guarantee performance-enhan-Particularly with the Olympic lifts we spend a lot of time just with the bar learning technique. ...
... 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. ...
Article
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.
... Because of the better lever ratios in the half [4] and quarter squat [17], considerably higher loads compared to the deep squat are necessary to induce the required training stimuli in hip and leg extensor muscles. Wirth and Zawieja [18] postulated target values of 1.5-2.0-fold ...
... For the half back squat, Dintiman and Ward [24] have described the following performance standards: 1.5ˆbodyweight represents a very poor, 1.8ˆbodyweight a poor, 2.1ˆbodyweight an average, and 2.7ˆbodyweight a good performance level. It has been reported that participants of a rather poor [17,25] to good performance level [26] reached relative loads of 2.2-to 2.7-fold bodyweight in the half squat after only 5-8 weeks [25,26] and even 3.89-fold bodyweight in the quarter squat after 10 weeks of training [17]. These associations between load level and squatting depth have not been discussed in reviews that have regarded stresses applied on the vertebral column [27]. ...
... For the half back squat, Dintiman and Ward [24] have described the following performance standards: 1.5ˆbodyweight represents a very poor, 1.8ˆbodyweight a poor, 2.1ˆbodyweight an average, and 2.7ˆbodyweight a good performance level. It has been reported that participants of a rather poor [17,25] to good performance level [26] reached relative loads of 2.2-to 2.7-fold bodyweight in the half squat after only 5-8 weeks [25,26] and even 3.89-fold bodyweight in the quarter squat after 10 weeks of training [17]. These associations between load level and squatting depth have not been discussed in reviews that have regarded stresses applied on the vertebral column [27]. ...
Article
Full-text available
For the development of speed strength in professional sports, “specific” strength training in the half or the quarter squat have been recommended. Due to the better lever ratios, higher loads have to be used to induce the necessary training stimuli compared to the deep squat. Therefore, intradiscal pressure and compressive forces on vertebral bodies increase. Calculated compressive forces for the L3/L4 vertebral segment were revealed to be 6–10-fold bodyweight when the half or the quarter squat was performed with 0.8–1.6-fold bodyweight. After 10 weeks of training, physical education students have even been able to lift 3.89-fold bodyweight in the one repetition maximum (1-RM) of the quarter squat. The presented dependence of squatting depth, load and their influence on the spinal column have not been discussed before. A search for relevant scientific literature was conducted using PubMed. Concerns about increased risk of injuries in the deep squat have been disproven by plenty of cross-sectional studies with professional athletes. On the contrary, the comparably supramaximal weight loads in the half and the quarter squat should be regarded as increasing injury risks caused by the higher shear and compressive forces in the vertebral column. Therefore, we come to the conclusion that the half and the quarter squat should not further be recommended.
... 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. ...
Article
Full-text available
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. ...
Article
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).
... 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. ...
Chapter
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.
... 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). ...
Article
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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.
... deeper is better (13,14). These apparent advantages to the squat may be attributed to a number of reasons. ...
... For one, the knee moved through a greater range of motion in the squat than it did in the leg press. As with previous studies that examined the effects of squat depth on performance (13,14), the subjects in this study were untrained or detrained, and were therefore conceivably more likely to realize greater adaptations from greater ranges of motion. Furthermore, it appears that the largest mechanical demands from the hip during the countermovement jump occur close to 45º (15), which is where the leg press movement was completed. ...
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Background: The purpose of this study was to compare strength, body composition, and functional outcome measures following performance of the back squat, leg press, or a combination of the two exercises. Methods: Subjects were pair-matched based on initial strength levels and then randomly assigned to 1 of 3 groups: A squat-only group (SQ) that solely performed squats for the lower body; a leg press-only group (LP) that solely performed leg presses for the lower body, or; a combined squat and leg press group (SQ-LP) that performed both squats and leg presses for the lower body. All other RT variables were held constant. The study period lasted 10 weeks with subjects performing 2 lower body workouts per week comprising 6 sets per session at loads corresponding to 8-12 RM with 90 to 120 second rest intervals. Results: Results showed that SQ had greater transfer to maximal squat strength compared to the leg press. Effect sizes favored SQ and SQ-LP versus LP with respect to countermovement jump while greater effect sizes for dynamic balance were noted for SQ-LP and LP compared to SQ, although no statistical differences were noted between conditions. Conclusions: These findings suggest that both free weights and machines can improve functional outcomes, and that the extent of transfer may be specific to the given task.
... 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. ...
Article
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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
... 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. ...
Article
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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.
... 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). ...
Article
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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.
... 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. ...
Article
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.
... Several technique variations of the squat exist [8,15,17,37,38], the main one consisting in modifying the squatting depth [1,2,17,39]. Research has shown that increases in lower-body strength following squat training transfer positively to athletic performance in short-duration actions that demand maximal neuromuscular activation such as sprinting and vertical jumping, especially when parallel or deep squats are used [11,18,21,23,[28][29][30]33]. ...
Article
The use of bar velocity to estimate relative load in the back squat exercise was examined. Eighty strength-trained men performed a progressive loading test to determine their one-repetition maximum (1RM) and load-velocity relationship. Mean (MV), mean propulsive (MPV) and peak (PV) velocity measures of the concentric phase were analyzed. Both MV and MPV showed a very close relationship to %1RM (R2 = 0.96), whereas a weaker association (R2 = 0.79) and larger SEE (0.14 vs. 0.06 m•s-1) was found for PV. Prediction equations to estimate load from velocity were obtained. When dividing the sample into three groups of different relative strength (1RM/body mass), no differences were found between groups for the MPV attained against each %1RM. MV attained with the 1RM was 0.32 ± 0.03 m•s-1. The propulsive phase accounted for 82% of concentric duration at 40% 1RM, and progressively increased until reaching 100% at 1RM. Provided that repetitions are performed at maximal intended velocity, a good estimation of load (%1RM) can be obtained from mean velocity as soon as the first repetition is completed. This finding provides an alternative to the often demanding, time-consuming and interfering 1RM or nRM tests and allows to implement a velocity-based resistance training approach.
... 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. ...
Article
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.
... The concentric phase was performed as quickly as possible whereas the eccentric 103 phase was executed more slowly (i.e.,~2 s). Due to the effect that the squatting depth has on acute and chronic responses 104[32] the range of motion (ROM) was matched in each exercise (i.e., until the thighs were parallel to the floor). The same percent-105 age of load (80% of one RM) was applied to all participants using feedback provided by a linear encoder device (SmartCoach106 ...
Article
Background: The analysis of structural changes in patellar tendon and muscle of healthy subjects in response to mechanical loads provides useful insight into the mechanism underlying overuse injuries. Methods: Changes produced in tendon and muscles structures after eccentric overload training and three consecutive running days were examined. Twenty healthy subjects were recruited and divided into two groups. One group (ECC) performed eccentric overload squat training (six weeks). After such training, the ECC group performed three running sessions on consecutive days, as did the control group (CONT). The structure of their patellar tendons and vastus lateralis muscles was quantified using ultrasound and Doppler imaging. Images were obtained before and after eccentric training for the ECC group and on every day of running performance for both groups. Results: After eccentric training, the ECC group experienced an increase in cross-sectional area (CSA) of patellar tendon (P=0.012). After every day of running, the ECC group experienced a decrease in CSA (P=0.027). In the CONT group, after one day of running a significant increase was observed in anteroposterior width of their patellar tendon (P=0.028), as well as a decrease in pennation angle of vastus lateralis muscle (P=0.028) within three days of running sessions. Conclusions: Eccentric overload training brought about changes in the patellar tendon consistent with an improvement in the quality of the tissue. The ECC group in our study showed a more normalised pattern than the CONT group in the running performance, in agreement with previous research. Level of evidence: Level 3, controlled trial.
... 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. ...
Article
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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. ...
Conference Paper
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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.
... • 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. ...
... A greater squat depth involves greater range of motion through these areas of the body [41]. Vertical jump performance is positively influenced by a higher range of motion through the hip, knee, and ankle during the countermovement [42], concurrent with the shoulders to instigate arm swing [43]. A unilateral vertical jump will also place great stress on the hip, knee, and ankle joints [21], and individuals that can attenuate these forces to a greater extent will typically perform better. ...
... 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. ...
Article
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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.
... 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. ...
Article
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.
... Furthermore, participants were no longer able to perform the parallel squat [173], which is why studies using the squat as a training exercise have not usually used a squatting depth beyond 90°knee angle. If deep squats were intended, the intensity would have to be reduced even further [174,175]; however, to create an adequate stimulus, a deep squat is desirable [167,174,176,177]. A combination of high loads with perturbations, such as unstable surfaces, is injury provoking [171,173]. ...
Article
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Over the last two decades, exercise of the core muscles has gained major interest in professional sports. Research has focused on injury prevention and increasing athletic performance. We analyzed the guidelines for so-called functional strength training for back pain prevention and found that programs were similar to those for back pain rehabilitation; even the arguments were identical. Surprisingly, most exercise specifications have neither been tested for their effectiveness nor compared with the load specifications normally used for strength training. Analysis of the scientific literature on core stability exercises shows that adaptations in the central nervous system (voluntary activation of trunk muscles) have been used to justify exercise guidelines. Adaptations of morphological structures, important for the stability of the trunk and therefore the athlete’s health, have not been adequately addressed in experimental studies or in reviews. In this article, we explain why the guidelines created for back pain rehabilitation are insufficient for strength training in professional athletes. We critically analyze common concepts such as ‘selective activation’ and training on unstable surfaces.
... The participants performed 3-5 repetitions respectively for SJ, CMJ and CMJarm with emphasis on form. After the warm-up, the subjects stood in an [25] the subjects performed the jump by bending the knees to a position they felt comfortable (i.e., preferred starting push-off position). A rest interval of 90 seconds was interspersed between jump repetitions, while 5 minutes was allowed between jump trials. ...
Article
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Common methods to estimate vertical jump height (VJH) are based on the measurements of flight time (FT) or vertical reaction force. This study aimed to assess the measurement errors when estimating the VJH with flight time using photocell devices in comparison with the gold standard jump height measured by a force plate (FP). The second purpose was to determine the intrinsic reliability of the Optojump photoelectric cells in estimating VJH. For this aim, 20 subjects (age: 22.50±1.24 years) performed maximal vertical jumps in three modalities in randomized order: the squat jump (SJ), counter-movement jump (CMJ), and CMJ with arm swing (CMJarm). Each trial was simultaneously recorded by the FP and Optojump devices. High intra-class correlation coefficients (ICCs) for validity (0.98-0.99) and low limits of agreement (less than 1.4 cm) were found; even a systematic difference in jump height was consistently observed between FT and double integration of force methods (-31% to -27%; p 1.2). Intra-session reliability of Optojump was excellent, with ICCs ranging from 0.98 to 0.99, low coefficients of variation (3.98%), and low standard errors of measurement (0.8 cm). It was concluded that there was a high correlation between the two methods to estimate the vertical jump height, but the FT method cannot replace the gold standard, due to the large systematic bias. According to our results, the equations of each of the three jump modalities were presented in order to obtain a better estimation of the jump height.
... 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). ...
Article
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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.
... 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). ...
Article
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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.
... ~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. ...
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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.
... These improvements in strength are in line with previous results from a combined strength and power training program. For example, Hartmann et al. 24 reported a 30.4% improvement in leg strength following 10-weeks of squat training using similar training intensities and a subject cohort similar to the present investigation. Similarly, Harris et al. 25 reported an 11% improvement in parallel squat 1RM and a 37% improvement in ¼ squat 1RM following nine weeks of training designed in highly competitive American Football players. ...
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There is currently minimal evidence from training studies that document the effectiveness of complex training to elicit gains in explosive muscle function that are greater than those obtained from a more conventional approach. Over nine weeks of training, 20 recreationally trained athletes with a minimum of one year of resistance training experience were randomly assigned to either a complex training group (n = 9) or a conventional training group (n = 11). In an attempt to capitalise on muscles post-activation potentiation response, the complex training group performed all sets of ½ back squats prior to sets of jumps squats, while the conventional training group performed jump squats prior to sets of ½ back squats. Lower body explosive muscle function and jump performance improved significantly in both groups. The complex training group’s improvement in running vertical jump performance was significantly greater than in the conventional groups. Sprint performance was not significantly improved in either training group.
... 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. ...
Article
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.
... 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]. ...
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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.
... 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] ...
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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.
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Das Anforderungsprofil des Fußballspieles zeigt, dass Maximal- und Schnellkraftleis-tungen einen leistungsdeterminierenden Faktor in dieser Sportart einnehmen. Krafttrai-ningsinterventionen im Kindes- und Jugendalter bis hin zum Erwachsenenalter führen zu Leistungsverbesserungen in Maximal- und Schnellkraftparametern. Ziel dieser Untersuchung ist es daher zu klären, ob und wie sich eine zweijährige Krafttrainingsintervention auf Maximal- und Schnellkraftleistungen jugendlicher Athleten aus dem Nachwuchsleistungssport auswirkt. An der zweijährigen Untersuchung nahmen 114 Probanden aus zwei Vereinen teil, die durch den Deutschen Fußball Bund e.V. mit dem Prädikat eines Leistungszentrums ausgezeichnet sind. Die Fußballer wurden in zwei Gruppen unterteilt. Die Fußballer wurden zusätzlich jeweils in Subgruppen nach Alter (unter 14 Jahren [U14], unter 16 Jahren [U16] und unter 18 Jahren [U18]) zugeordnet. Die eine Gruppe (KT) führte zweimal wöchentlich zusätzlich zum regulären Fußballtraining ein Krafttraining durch, die andere Gruppe (KG) absolvierte ausschließlich das reguläre Fußballtraining. Es wurde die Leistungsfähigkeit im Squat- (SJ), Countermovement- (CMJ) und Drop Jump (DJ) aus unterschiedlichen Höhen (16 bis 40 Zentimeter), sowie Maximalkraftleistungen im Ei-ner-Wiederholungs-Maximum (1RM) der Front- und Nackenkniebeuge vor, nach einem Jahr und nach der zweijährigen Trainingsphase erfasst. Zur Kontrolle des Einflussfak-tors Wachstum wurden in diesem Forschungsprojekt Querschnittsdaten im SJ, CMJ und DJ von insgesamt 426 Schülern (männlich) im Alter zwischen 12 und 19 Jahren analog zu den Fußballern erhoben. Die Schüler wurden in Altersklassen (U13 bis U19) eingeteilt. Für die Analyse der Leistungsentwicklung innerhalb einer Gruppe und die paarweisen Vergleiche zwischen zwei Gruppen wurde eine zweifaktorielle Varianzanalyse mit Messwiederholung mit den Faktoren Gruppe und Zeit durchgeführt. Im Falle signifikan-ter F-Werte wurde eine Post-hoc-Analyse (Scheffe) durchgeführt, um die Lokalisation der signifikanten Veränderungen zu errechnen. Die Analyse der Querschnittsdaten er-folgte über die einfaktorielle Varianzanalyse. Die Post-hoc-Analyse (Scheffe) zeigte statistisch signifikante Leistungsunterschiede zwischen den Altersklassen auf (paarwei-se Vergleiche zwischen zwei Altersstufen). Zur Ermittlung von Zusammenhängen zwi-schen verschiedenen Parametern wurde die Produkt-Moment-Korrelation nach Pearson berechnet. Das Signifikanzniveau wurde für alle statistischen Verfahren auf p < 0,05 festgelegt. Im Vergleich der Fußballer schnitt die Krafttrainingsgruppe nach der zweijährigen Untersuchungsdauer in den Maximalkraftleistungen der Front- und Nackenkniebeuge in allen Altersklassen signifikant besser ab. Die Ergebnisse der KG zeigen in der U18 für die Maximalleistungen bei den Kniebeugen über zwei Jahre Steigerungen im Mittel von 9,3 ± 13,1 bis 37,1 ± 21,4%, in der U16 von 48,3 ± 39,7 bis 62,1 ± 53,3% und in der U14 von 84,4 ± 26,1 bis 94 ± 39,8%. Die Leistungssteigerungen der KT in den Maxi-malkraftparametern übersteigen die Zunahmen der KG bei Weitem. In der U14 finden sich je nach Parameter zwischen 290,9 ± 107,7 bis 312,6 ± 118,6% Leistungssteigerung über zwei Jahre. Die U16 weist 112,4 ± 32,7 bis 121,4 ± 39,4% Leistungssteigerung auf und die U18 zwischen 104,0 ± 45,6 bis 106,0 ± 34,4% Leistungssteigerung je nach Pa-rameter über zwei Jahre. Im Squat Jump zeigte die KT ebenfalls signifikant bessere Leistungen (U18: 26,1 ± 13,9%, U16: 29,7 ± 16,7%, U14: 30,9 ± 13,8%), als die Gruppe, die kein Krafttraining absolvierte (U18: 1,0 ± 8,7%, U16: 10,4 ± 11,8%, U14: 8,1 ± 9,9%). Ähnliche signifikante Steigerungsraten wurden beim Countermovement Jump (U18: 20,3 ± 14,0% vs. 1,2 ± 6,9%, U16: 21,2 ± 14,4% vs. 11,1 ± 10,5%, U14: 21,6 ± 14,4% vs. 9,9 ± 7,7%) zugunsten der KG ermittelt. Die U18 der KT weist im Mittel Steigerungen des Drop Jump in den jeweiligen Höhen von 6,6 ± 16,9 bis 14,8 ± 21,3% auf. Es wurden keine signifikanten Unterschiede zur KG analysiert (Steigerungen: 0,0 ± 20 bis 6,2 ± 27,0%). Die U16 der KT erreicht Steigerungen im DJ im Mittel von 35,8 ± 28,8 bis 36,9 ± 22,5%. Dies führte zu signifikanten Unterschieden gegenüber der KG, die Steigerungen von 15,1 ± 20,8 bis 22,0 ± 19,0% aufwies. Zwischen den Gruppen der U14 kam es zu signifikanten Unterschieden im Ausgangstest. Die KT der U14 wies höhere Steigerungen (29,2 ± 25,8 bis 41,3 ± 29,3%) auf als die KG (1,5 ± 18,3 bis 15,2 ± 30,8%). Die Abschätzung der Leistungsentwicklung in den Schnellkraftparametern zeigte, dass es mit dem Alter zu leistungspositiven Veränderungen kommt. Unterstellt man, dass die Differenz zwischen den Mittelwerten der Leistungsparameter der einzel-nen Altersklassen der untrainierten Schüler die entwicklungsbedingte Leistungsentwick-lung darstellt, finden sich die höchsten Zunahmen zwischen den Altersklassen der U13 und der U17 und die geringsten Zunahmen bei den ältesten Jugendlichen. Die Gruppen-vergleiche erreichten nicht zwischen allen Altersstufen signifikantes Niveau, sondern zum Teil erst zu mindestens zwei Jahre älteren Probandengruppen. Die Zusammenhangsanalysen zeigen hohe Zusammenhänge zwischen dem SJ und CMJ und den Maximalkraftparametern. Die Zusammenhänge zwischen den Maximalkraftparametern und den Leistungen im DJ klassifizieren sich als gering bis mittel. Die Daten zeigen, dass sowohl dem Faktor körperliche Entwicklung, als auch der Sportart Fußball leistungspositive Einflüsse auf Schnellkraftleistungen zugeordnet wer-den können. Die Datenlage dieser Untersuchung zeigt ferner, dass ein Krafttraining ei-nen positiven Effekt auf Leistungsparameter im Fußball hat. Eine langfristige Trai-ningsintervention von zwei Jahren kann zu einer deutlichen Steigerung des 1RM, des SJ, des CMJ und des DJ führen. Die Maximal- und Schnellkraft ist demnach im Ju-gendalter durch ein langfristig angelegtes Krafttraining sehr gut zu steigern. Demnach ist ein ergänzendes Krafttraining im Nachwuchsleistungssport der Sportart Fußball zu empfehlen.
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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.
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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.
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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.
Chapter
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).
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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.
Thesis
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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.
Article
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.
Thesis
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.
Article
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.
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The barbell hip thrust may be an effective exercise for increasing horizontal force production and may thereby enhance performance in athletic movements requiring a horizontal force vector, such as horizontal jumping and sprint running. The ergogenic ability of the squat is well known. The purpose of this study was to compare the effects of six-week front squat and hip thrust programs in adolescent male athletes. Vertical jump height, horizontal jump distance, 10 m and 20 m sprint times, and isometric mid-thigh pull peak force were among the measured performance variables, in addition to front squat and hip thrust three-repetition maximum (3 RM) strength. Magnitude-based effect-sizes revealed potentially beneficial effects for the front squat in both front squat 3 RM strength and vertical jump height when compared to the hip thrust. No clear benefit for one intervention was observed for horizontal jump performance. Potentially beneficial effects were observed for the hip thrust compared to the front squat in 10 m and 20 m sprint times. The hip thrust was likely superior for improving normalized isometric mid-thigh pull strength, and very likely superior for improving hip thrust 3 RM and isometric mid-thigh pull strength. These results support the force vector theory.
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