Article

Electromyographic Activity of the Hamstrings During Performance of the Leg Curl, Stiff-Leg Deadlift, and Back Squat Movements

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Abstract

To compare the effectiveness of 3 weight-training movements for the hamstrings, 11 weight-trained men performed 3 repetitions at 75% of 1 repetition maximum of the leg curl (LC), stiff-leg deadlift (SLDL), and back squat. Integrated electromyography (EMG) and peak EMG were analyzed in the biceps femoris and semitendinosus independantly during the concentric (CON) and eccentric (ECC) phase of each exercise. Results were as follows: CON-LC and CON-SLDL elicited the greatest integrated EMG activity, with no significant difference between exercises. The CON-squat showed approximately half as much integrated EMG activity as CON-LC and CON-SLDL. Highest peak EMG was found in the CON-LC and CON-SLDL, with no significant difference in these exercises. The CON-squat produced a peak EMG that was approximately 70% of LC and SLDL. We conclude that LC and SLDL involve the hamstrings to a similar degree; however, the back squat involves only about half as much hamstring integrated EMG activity as LC and SLDL. (C) 1999 National Strength and Conditioning Association

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... In the hamstrings, the greater intra-muscular activation (Figure 4) of the semitendinosus muscle compared to that of the biceps femoris account for its predominance [52,53]. A balance in the synergy of the hamstring muscles is important in the reduction of risk of a potential injury [53]. ...
... In the hamstrings, the greater intra-muscular activation (Figure 4) of the semitendinosus muscle compared to that of the biceps femoris account for its predominance [52,53]. A balance in the synergy of the hamstring muscles is important in the reduction of risk of a potential injury [53]. This synergy helps to reduce the tension on the biceps femoris [21,54], which plays a fundamental role in the hamstring injury, since biceps femoris is affected in 80% of all hamstring lesions [55]. ...
... For the hamstrings muscles, there was greater activation in all phases in the Bulgarian squat ( Figure 5) than in the normal squat (Figure 7), which may be due to a greater demand for co-activation of the posterior leg musculature to keep joints and the body stable [62]. Wright and Delong [53] emphasized the importance of the posterior muscles in exercises such as the Bulgarian squat, where the knee joint was fixed, thereby increasing the activation of the hamstrings. ...
Article
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This study aimed to study the coactivation patterns of the hamstring and quadriceps muscle groups during submaximal strength exercises commonly used in injury prevention in soccer without the use of maximum voluntary isometric contraction testing. This was used to compare: (i) the inter-limb differences in muscle activation; (ii) the intra-muscular group activation pattern and (iii) the activation pattern during different phases of the exercise. Muscle activation was recorded by surface electromyography in 19 elite, male, youth soccer players. Participants performed the following: Bulgarian squat, lunge and squat. Electrical activity was recorded for the rectus femoris, vastus medialis, vastus lateralis, biceps femoris and semitendinosus. No significant inter-limb differences were found (F1, 13 = 619; p = 0.82; η2 = 0.045). Significant differences were found in the muscle activation between individual muscles within the quadriceps and hamstrings muscle group for each of the exercises: Bulgarian squat (F1,18 = 331: p < 0.001; η2 = 0.80), lunge (F4,72 = 114.5; p < 0.001; η2 = 0.86) and squat (F1,16 = 247.31; p < 0.001; η2 = 0.93). Differences were found between the different phases of each of the exercises (F2,26 = 52.27; p = 0.02; η2 = 0.80). The existence of an activation pattern of each of the muscles in the three proposed exercises could be used for muscle assessment and as a tool for reconditioning post-injury.
... Furthermore, individuals also use variations of the deadlift, such as the Romanian deadlift in rehabilitation settings, such as late-stage anterior cruciate ligament (ACL) injury recovery. The activation of the hamstrings in the deadlift may protect the ACL during knee rehabilitation because it provides an additional posterior force on the tibia (12,38). The back-squat also targets the hip and knee extensors and is effective in improving lower extremity strength and athletic performance (7,29,30). ...
... However, the study was not performed in a laboratory setting, and kinetic variables, such as joint moments, were not investigated (18). The hamstrings have higher electromyography (EMG) activity (38), but lower quadriceps EMG activity during the deadlift compared with the back-squat (11). There is paucity in the literature regarding joint kinetics of the back-squat and deadlift. ...
... This finding suggests that because of the increase in rate of torque development, the deadlift may have positive transfer to highly explosive and time sensitive tasks. When considering findings of previous investigations (32,38), the deadlift seems to be an effective exercise that can benefit multiple populations. For example, strength and conditioning coaches would also benefit from this finding, as programming deadlifts into training regimens would benefit their athletes' performance. ...
Article
Choe, KH, Coburn, JW, Costa, PB, and Pamukoff, DN. Hip and knee kinetics during a back-squat and deadlift. J Strength Cond Res XX(X): 000-000, 2018-The back-squat and deadlift are performed to improve hip and knee extensor function. The purpose of this study was to compare lower extremity joint kinetics (peak net joint moments [NJMs] and positive joint work [PJW]) between the back-squat and deadlift. Twenty-eight resistance-trained subjects (17 men: 23.7 ± 4.3 years, 1.76 ± 0.09 m, 78.11 ± 10.91 kg; 11 women: 23.0 ± 1.9 years, 1.66 ± 0.06 m, 65.36 ± 7.84 kg) were recruited. One repetition maximum (1RM) testing and biomechanical analyses occurred on separate days. Three-dimensional biomechanics of the back-squat and deadlift were recorded at 70 and 85% 1RM for each exercise. The deadlift demonstrated larger hip extensor NJM than the back-squat {3.59 (95% confidence interval [CI]: 3.30-3.88) vs. 2.98 (95% CI: 2.72-3.23) Nm·kg, d = 0.81, p < 0.001}. However, the back-squat had a larger knee extensor NJM compared with the deadlift (2.14 [95% CI: 1.88-2.40] vs. 1.18 [95% CI: 0.99-1.37] Nm·kg, d = 1.44 p < 0.001). More knee PJW was performed during the back-squat compared with the deadlift (1.85 [95% CI: 1.60-2.09] vs. 0.46 [95% CI: 0.35-0.58] J·kg, d = 2.10, p < 0.001). However, there was more hip PJW during the deadlift compared with the back-squat (3.22 [95% CI: 2.97-3.47] vs. 2.37 [95% CI: 2.21-2.54] J·kg, d = 1.30, p < 0.001). Larger hip extensor NJM and PJW during the deadlift suggest that individuals targeting their hip extensors may yield greater benefit from the deadlift compared with the back-squat. However, larger knee extensor NJM and PJW during the back-squat suggest that individuals targeting their knee extensor muscles may benefit from incorporating the back-squat compared with the deadlift.
... Surface electromyographic (sEMG) data were recorded for the Vastus Lateralis (VL) and Vastus Medialis (VM) during all protocol conditions (Criswell & Cram 2011). For analysis, three central repetitions of each set were considered (Wright et al. 1999). Before EMG acquisition, appropriate preparation of the skin was carried out to remove body hair, oils, and flaky skin layers and, consequently, reduce the impedance in the electrode-gel-skin interface. ...
... The sEMG values were determined by an average of the sEMG values of three central repetitions of each set (Farias et al. 2017). Normalization was carried out using the highest peak sEMG value (Wright et al. 1999;Farias et al. 2017). All data processing was carried out in MATLAB ® (Natick, MA, USA). ...
Article
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The aim of the present study was to investigate the influence of intensity of load and cuff pressure on training volume and myoelectric activation during the knee extension exercise executed with and without blood flow restriction (BFR) to failure. Ten young men (22 ± 2 y), with at least six months of training experience, visited the laboratory on eight non-consecutive days with intervals of at least 48 hours between sessions. In the first two visits, one-repetition maximum (1RM) test and retest were performed in the unilateral knee extension exercise. In the subsequent six visits, the subjects performed resistance training sessions (4 sets to concentric failure) at different load intensities (30, or 40% of 1RM) and BFR pressures (0, 100, or 150mmHg). The restriction cuff was of 18-cm width and was positioned on the superior 1/3 of the thigh. Measures of training volume, and myoelectric activity from the vastus lateralis and vastus medialis via surface electromyographic, were recorded. During experimental sessions, it was observed that the use of BFR significantly reduced the training volume, independently of the load used. Less repetitions were performed with a restriction pressure of 150mmHg (47 ± 10) compared to 0mmHg (61 ± 15) and 100mmHg (59 ± 17), and with 30%1RM (50 ± 14) compared to 40%1RM (61 ± 15). For surface electromyography measures, no significant differences were observed between the conditions (P>0.05). In conclusion, the application of BFR to low-load knee extension exercise to failure led to lower training volume but did not influence myoelectric activity.
... Some studies using surface electromyography (sEMG) have been proposed to verify differences in muscle activity during priority and complementary exercises for the upper (Botton et al., 2013;Franke et al., 2015) and lower (Ema et al., 2016;Wright et al., 1999) limbs. Wright et al. (1999) found greater muscle activation in the semitendinosus and biceps femoris muscles during knee flexion when compared to squats. ...
... Some studies using surface electromyography (sEMG) have been proposed to verify differences in muscle activity during priority and complementary exercises for the upper (Botton et al., 2013;Franke et al., 2015) and lower (Ema et al., 2016;Wright et al., 1999) limbs. Wright et al. (1999) found greater muscle activation in the semitendinosus and biceps femoris muscles during knee flexion when compared to squats. Ema et al. (2016) found greater muscle activity in the rectus femoris during knee extension compared to the leg press. ...
Article
Full-text available
The aims of this study were to compare muscle activity of the anterior deltoid, medial deltoid, and posterior deltoid in the bench press, dumbbell fly, shoulder press, and lateral raise exercises. Thirteen men experienced in strength training volunteered for the study. Muscle activation was recorded during maximum isometric voluntary contraction (MVIC) for data normalization, and during one set of 12 repetitions with the load of 60% 1RM in all exercises proposed. One-way repeated-measures ANOVA with Bonferroni's posthoc was applied using a 5% significance level. For anterior deltoid, the shoulder press (33.3% MVIC) presented a significantly higher level of activation when compared to other exercises. Also, no significant difference was found between the bench press (21.4% MVIC), lateral raise (21.2% MVIC), and dumbbell fly (18.8% MVIC). For the medial deltoid, the lateral raise (30.3% MVIC) and shoulder press (27.9% MVIC) presented a significantly higher level of activity than the bench press (5% MVIC) and dumbbell fly (3.4% MVIC). Besides, no significant difference was found between the bench press and the dumbbell fly. For the posterior deltoid, the lateral raise (24% MVIC) presented a significantly higher level of activation when compared to other exercises. For the posterior deltoid portion, the shoulder press (11.4% MVIC) was significantly more active than the bench press (3.5% MVIC) and dumbbell fly (2.5% MVIC). Moreover, no significant difference was found between the bench press and the dumbbell fly. In conclusion, the shoulder press and lateral raise exercises showed a higher level of muscle activation in the anterior deltoid and medial deltoid when compared to the bench press and dumbbell fly exercises.
... Some studies using surface electromyography (sEMG) have been proposed to verify differences in muscle activity during priority and complementary exercises for the upper (Botton et al., 2013;Franke et al., 2015) and lower (Ema et al., 2016;Wright et al., 1999) limbs. Wright et al. (1999) found greater muscle activation in the semitendinosus and biceps femoris muscles during knee flexion when compared to squats. ...
... Some studies using surface electromyography (sEMG) have been proposed to verify differences in muscle activity during priority and complementary exercises for the upper (Botton et al., 2013;Franke et al., 2015) and lower (Ema et al., 2016;Wright et al., 1999) limbs. Wright et al. (1999) found greater muscle activation in the semitendinosus and biceps femoris muscles during knee flexion when compared to squats. Ema et al. (2016) found greater muscle activity in the rectus femoris during knee extension compared to the leg press. ...
Preprint
Full-text available
The aims of this study were to compare muscle activity of the anterior deltoid, medial deltoid, and posterior deltoid in the bench press, dumbbell fly, shoulder press, and lateral raise exercises. Thirteen men experienced in strength training volunteered for the study. Muscle activation was recorded during maximum isometric voluntary contraction (MVIC) for data normalization, and during one set of 12 repetitions with the load of 60% 1RM in all exercises proposed. One-way repeated-measures ANOVA with Bonferroni's posthoc was applied using a 5% significance level. For anterior deltoid, the shoulder press (33.3% MVIC) presented a significantly higher level of activation when compared to other exercises. Also, no significant difference was found between the bench press (21.4% MVIC), lateral raise (21.2% MVIC), and dumbbell fly (18.8% MVIC). For the medial deltoid, the lateral raise (30.3% MVIC) and shoulder press (27.9% MVIC) presented a significantly higher level of activity than the bench press (5% MVIC) and dumbbell fly (3.4% MVIC). Besides, no significant difference was found between the bench press and the dumbbell fly. For the posterior deltoid, the lateral raise (24% MVIC) presented a significantly higher level of activation when compared to other exercises. For the posterior deltoid portion, the shoulder press (11.4% MVIC) was significantly more active than the bench press (3.5% MVIC) and dumbbell fly (2.5% MVIC). Moreover, no significant difference was found between the bench press and the dumbbell fly. In conclusion, the shoulder press and lateral raise exercises showed a higher level of muscle activation in the anterior deltoid and medial deltoid when compared to the bench press and dumbbell fly exercises.
... Os músculos isquiotibiais (semitendinoso, semimembranoso e bíceps femoral) também atuam no agachamento, promovendo a extensão do quadril. Porém, diferentemente do glúteo máximo, sua participação é moderada durante o agachamento (8,36) . A ativação dos isquiotibiais durante o agachamento é de, aproximadamente, metade da ativação quando comparada a exercícios isolados de extensão de quadril (stiff) e flexão de joelhos (mesa flexora) (36) . ...
... Porém, diferentemente do glúteo máximo, sua participação é moderada durante o agachamento (8,36) . A ativação dos isquiotibiais durante o agachamento é de, aproximadamente, metade da ativação quando comparada a exercícios isolados de extensão de quadril (stiff) e flexão de joelhos (mesa flexora) (36) . Essa ativação moderada no agachamento ocorre devido à natureza biarticular dos músculos isquiotibiais. ...
... The specific development of these muscles can be performed by both single-joint and multijoint exercises (17). However, during multijoint exercises, the hamstrings are considered synergists and present moderate to low muscle activity during squats (3,4,13,24), leg press (6), and lunges (14). Thus, the incorporation of single-joint exercises such as the prone leg curl is recommended as part of a complete training program for lower limbs (20), producing approximately twice as much hamstring activation compared with the squat exercise (24). ...
... However, during multijoint exercises, the hamstrings are considered synergists and present moderate to low muscle activity during squats (3,4,13,24), leg press (6), and lunges (14). Thus, the incorporation of single-joint exercises such as the prone leg curl is recommended as part of a complete training program for lower limbs (20), producing approximately twice as much hamstring activation compared with the squat exercise (24). In addition, the gastrocnemius (lateral and medial head) present biarticular characteristics and act as both primary knee flexors and ankle plantarflexors (10,21); it is plausible that these muscles may affect the knee flexion in different ankle positions. ...
Article
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Marchetti, PH, Magalhaes, RA, Gomes, WA, da Silva, JJ, Stecyk, SD, and Whiting, WC. Different knee and ankle positions affect force and muscle activation during prone leg curl in trained subjects. J Strength Cond Res XX(X): 000-000, 2019-Different joint positions for biarticular muscles may affect force and muscular activity during single-joint exercises. The aim of this study was to compare the maximal isometric contractions and muscle activation in 2 different knee and ankle positions during prone leg curl exercise in trained subjects. Fifteen resistance-trained men (27 ± 4 years, 178.80 ± 5.72 cm, 86.87 ± 12.51 kg) were recruited. The peak force (PF) and muscle activation of biceps femoris, gastrocnemius lateralis (GL), and soleus lateralis (SL) were measured during knee flexion at 0 and 90° and maximal dorsiflexion (D) or plantarflexion (P). Three maximal voluntary isometric contractions of 5 seconds were performed for each combination of knee and ankle positions. Two-way repeated-measures analysis of variances were used for all dependent variables. For PF, there was a significant difference between ankle positions (D × P) at 90° (p = 0.009) and knee positions (0 × 90°) for D (p < 0.001) and P (p < 0.001). Peak force was greater with the knee at 0° and the ankle maximally dorsiflexed. For GL, there was a significant difference between ankle (D × P) at 0° (p = 0.002) and knee positions (0 × 90°) for D (p = 0.005). Gastrocnemius lateralis activation was greater with the knee at 90° of flexion and the ankle maximally dorsiflexed. For SL, there was a significant difference between ankle positions (D × P): at 90° (p = 0.001) and at 0° (p = 0.002). Soleus lateralis is more active in plantarflexion irrespective of the knee joint position. Isometric contractions with full knee extension produce more strength regardless of the ankle position; neither the knee position nor the ankle position may influence the activity of the hamstrings.
... However, if the participants' 1RM attempt was unsuccessful, the weight was reduced and the attempted was tried again until successful (12). Once the 1RMs were determined, participants were given 10 minutes of rest before performing the set of 3 repetitions at 75% 1RM for the first exercise (23). Repetitions were performed at a pace of 2 seconds for the eccentric action and 1 second for the concentric action with a 2-second pause between repetitions set by a metronome (14). ...
... The great majority of previous literature examining lowerbody muscle activity during a squat protocol has primarily included the back squat (10,13,14,22,23). Gullett et al. (11) found no difference in muscle activity between the front squat and the back squat with exercise loads of 70% 1RM, similar to the loads in the current study (i.e., 75% 1RM). ...
Article
The deadlift and back and front squats are common multijoint, lower-body resistance exercises that target similar musculature. To our knowledge, muscle activity measured using surface electromyography has never been analyzed among these 3 exercises. Furthermore, most literature examining this topic has included male participants creating a void in the literature for the female population. Knowledge of lower-body muscle activation among these 3 exercises can aid coaches, trainers, and therapists for training and rehabilitative purposes. Trained women (n = 13) completed 2 days of testing including a 1-repetition maximum (1RM) estimation, an actual 1RM, and 3 repetitions at 75% 1RM load for the deadlift and back and front squats. Muscle activity of the 3 repetitions of each muscle was averaged and normalized as a percentage to the 1RM lifts for the deadlift and front and back squats. Five separate repeated-measure analysis of variances were performed indicating muscle activity of the gluteus maximus (GM) differed among the 3 exercises (p = 0.01, (Equation is included in full-text article.)= 0.39). Specifically, post hoc analysis indicated greater muscle activity during the front squat (M = 94%, SD = 15%) compared with the deadlift (M = 72%, SD = 16%; p ≤ 0.05) in the GM. No significant differences were observed among the lifts in the vastus medialis, vastus lateralis, biceps femoris, and rectus femoris. Strength and conditioning specialist and trainers can use these findings by prescribing the front squat to recruit greater motor units of the GM.
... But, the 15 of knee flexion is a slight knee bend position that was used as the SLD in some studies. 5,7,8 Therefore, the purpose of the present study was to determine which deadlift technique is a better training protocol between the CD and the RD as indicated by the greater demand in the muscle activities and joint kinetics. To achieve the purpose, electromyographic and kinetic variables between the CD and the RD were compared. ...
... The 15 of knee flexion means the knees are in a slightly flexed position that was defined as the SLD in some studies. 5,7,8 The 15 of knee flexion reported was inconsistent with the average knee flexion angle (33 ) observed during the RD in the current study (Table 3). This discrepancy may be due to different vertical barbell displacements. ...
Article
Full-text available
Background/objective Significant biomechanical differences were found among deadlift variations. However, little is known about the differences between the conventional and the Romanian deadlifts. Therefore, the purpose of this study was to determine which deadlift technique is a better training protocol between the conventional and the Romanian deadlifts as indicated by the greater demand in muscle activities and joint kinetics. Methods 21 males performed each deadlift with 70% of the Romanian deadlift one repetition maximum (1RM) determined using a 1RM testing. Myoelectric activities of the rectus femoris, biceps femoris, and gluteus maximus and lower extremity net joint torque (NJT) were compared. The variables were extracted through an electromyography system (EMG) and a three-dimensional motion analysis. The EMG values were normalized to the peak EMG activation from a submaximal non-isometric voluntary contraction. A two-way repeated measures analysis of variance was conducted for statistical analysis. The level of significance was set at 0.05. Results Significantly greater normalized EMG values were found from the rectus femoris and gluteus maximus (58.57 ± 13.73 and 51.52 ± 6.08 %peak) of the conventional deadlift than those of the Romanian deadlift (25.26 ± 14.21 and 46.88 ± 7.39 %peak). The conventional deadlift indicated significantly greater knee and ankle NJTs (0.21 ± 0.13 and −0.33 ± 0.08 Nm/kg cm) than those of the Romanian deadlift (−0.28 ± 0.1 and −0.29 ± 0.06 Nm/kg cm). Conclusion The conventional deadlift would be a better technique for training the rectus femoris and gluteus maximus than the Romanian deadlift as indicated by the greater EMG and NJT values.
... However, if the participants' 1RM attempt was unsuccessful, the weight was reduced and the attempted was tried again until successful (12). Once the 1RMs were determined, participants were given 10 minutes of rest before performing the set of 3 repetitions at 75% 1RM for the first exercise (23). Repetitions were performed at a pace of 2 seconds for the eccentric action and 1 second for the concentric action with a 2-second pause between repetitions set by a metronome (14). ...
... The great majority of previous literature examining lowerbody muscle activity during a squat protocol has primarily included the back squat (10,13,14,22,23). Gullett et al. (11) found no difference in muscle activity between the front squat and the back squat with exercise loads of 70% 1RM, similar to the loads in the current study (i.e., 75% 1RM). ...
... 3. Under the professional's guidance, use unilateral knee flexions on a Swiss ball to strengthen the hamstrings and possibly reduce a bilateral strength deficit 28,29 . 4. Under the professional's guidance, use unilateral or bilateral Romanian deadlifts, the good morning exercise, or both to strengthen the hip extension function of hamstrings 28,30,31 . ...
... Under the professional's guidance, use unilateral knee flexions on a Swiss ball to strengthen the hamstrings and possibly reduce a bilateral strength deficit 28,29 . 4. Under the professional's guidance, use unilateral or bilateral Romanian deadlifts, the good morning exercise, or both to strengthen the hip extension function of hamstrings 28,30,31 . ...
Article
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Many hamstring injuries that occur during physical activity occur while the muscles are lengthening, during eccentric hamstring muscle actions. Opposite of these eccentric hamstring actions are concentric quadriceps actions, where the larger and likely stronger quadriceps straighten the knee. Therefore, to stabilize the lower limbs during movement, the hamstrings must eccentrically combat against the strong knee-straightening torque of the quadriceps. As such, eccentric hamstring strength expressed relative to concentric quadricep strength is commonly referred to as the "functional ratio" as most movements in sports require simultaneous concentric knee extension and eccentric knee flexion. To increase the strength, resiliency, and functional performance of the hamstrings, it is necessary to test and train the hamstrings at different eccentric speeds. The main purpose of this work is to provide instructions for measuring and interpreting eccentric hamstring strength. Techniques for measuring the functional ratio using isokinetic dynamometry are provided and sample data will be compared. Additionally, we briefly describe how to address hamstring strength deficiencies or unilateral strength differences using exercises that specifically focus on increasing eccentric hamstring strength.
... However, if the participants' 1RM attempt was unsuccessful, the weight was reduced and the attempted was tried again until successful (20). Once the 1RMs were determined, participants were given 10 minutes of rest before performing the set of 3 repetitions at 75% 1RM for the first exercise (23). Repetitions were performed at a pace of 2 seconds for the eccentric action and 1 second for the concentric action with a 2-second pause between repetitions set by a metronome (13). ...
... The great majority of previous literature examining lowerbody muscle activity during a squat protocol has primarily included the back squat (9,12,13,22,23). Gullett et al. (11) found no difference in muscle activity between the front squat and the back squat with exercise loads of 70% 1RM, similar to the loads in the current study (i.e., 75% 1RM). ...
Article
Full-text available
The deadlift and back and front squats are common multi-joint, lower body resistance exercises that target similar musculature. To our knowledge, muscle activity measured via surface electromyography (EMG) has never been analyzed among these three exercises. Furthermore, most literature examining this topic has included male participants creating a void in the literature for the female population. Knowledge of lower body muscle activation among these three exercises can aid coaches, trainers, and therapists for training and rehabilitative purposes. Trained women (n = 13) completed two days of testing including a one repetition maximum (1RM) estimation, an actual 1RM, and 3 repetitions at 75% 1RM load for the deadlift and back and front squats. Muscle activity of the 3 repetitions of each muscle were averaged and normalized as a percentage to the 1RM lifts for the deadlift, front and back squats. Five separate repeated measure Analysis of Variances were performed indicating muscle activity of the gluteus maximus differed among the three exercises (p = .01, ηp2 = .39). Specifically, post hoc analysis indicated greater muscle activity during the front squat (M = 94%, SD = 15%) compared to the deadlift (M = 72%, SD = 16%; p < .05) in the gluteus maximus. No significant differences were observed among the lifts in the vastus medialis, vastus lateralis, biceps femoris, and rectus femoris. Strength and conditioning specialist and trainers can utilize these findings by prescribing the front squat to recruit greater motor units of the gluteus maximus.
... A ativação dos isquiotibiais durante o leg-press e a mesa extensora foram significativamente menores comparados ao agachamento. WRIGHT et al. (1999) Tanto ECCF quanto ECCA têm sido indicados para tratamento de distúrbios patelares. Numa comparação entre ECCF e ECCA para calcular as forças que agiam sobre a patela verificou-se que entre 0-50º de flexão do joelho, os ECCF produziram uma menor FCP, enquanto que entre 50-90º de flexão, os ECCA produziram uma menor FCP com relação ao ECCF (STEINKAMP et al., 1993). ...
... Comparados ao agachamento, o leg-press e a mesa extensora obtiveram uma ativação dos isquiotibiais significativamente menor, o que já era esperado levando-se em consideração que o maior objetivo destes exercícios é o desenvolvimento dos quadríceps. Porém, no estudo de WRIGHT et al. (1999) que buscou comparar o agachamento à mesa flexora e ao levantamento stiff, que são exercícios específicos para isquiotibiais, o agachamento demonstrou uma atividade EMG de aproximadamente 70% dos outros dois exercícios, o que indica que apesar do agachamento ser eficiente para o trabalho dos isquiotibiais, se o objetivo for um maior desenvolvimento desta musculatura, incluir a mesa flexora ou o stiff no programa de treinamento pode apresentar alguma vantagem. ...
Conference Paper
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The squat is among the more known and used exercises in resistance training, but some controversies about the prescription of this exercise had appeared through the years. The main sources of search for this review had been the database PubMed and MedLine ovid. It can be concluded that the squat is an excellent exercise for the development of quadriceps, hamstrings and gluteus maximus. Tibiofemoral compressive forces have great importance in stabilizing the knee, becoming the squat an excellent exercise in the rehabilitation of anterior cruciate ligament and posterior cruciate ligament (PCL). For the PCL and patella, it is recommended to squat between 0-50º knee flexion. It does not have because to hinder that individuals with healthy knees realize full squats. The spine must remain erect during the exercise and the Valsalva maneuver and the use of abdominal belts reveal efficient in promote intra-abdominal pressure, what it generates greater stability of the spine.
... Previous authors have also found greater activation of semitendinosus vs biceps femoris for the single leg Roman dead-lift T-drop with 12 repetition maximum load and kettle bell swings. 18,21 These findings may be partially explained by the fact that the semitendinosus is a fusiform muscle with parallel fibers and long fiber lengths, whereas biceps femoris and semimembranosus have a unipennate and bipennate arrangement. 22,23 Given these characteristics, semitendinosus may be more sensitive to exercise involving a large change in MTU length, such as when hip flexion actions are required. ...
... Tsaklis et al compared with concentric muscle action. 21,25 In a rehabilitation context, speed needs to be considered in relation to the symptoms and healing phase. ...
Article
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Hamstring injuries are common in many sports, including track and field. Strains occur in different parts of the hamstring muscle but very little is known about whether common hamstring loading exercises specifically load different hamstring components. The purpose of this study was to investigate muscle activation of different components of the hamstring muscle during common hamstring loading exercises. Twenty elite female track and field athletes were recruited into this study, which had a single-sample, repeated-measures design. Each athlete performed ten hamstring loading exercises, and an electromyogram (EMG) was recorded from the biceps femoris and semitendinosus components of the hamstring. Hamstring EMG during maximal voluntary isometric contraction (MVIC) was used to normalize the mean data across ten repetitions of each exercise. An electrogoniometer synchronized to the EMG was used to determine whether peak EMG activity occurred during muscle-tendon unit lengthening, shortening, or no change in length. Mean EMG values were compared between the two recording sites for each exercise using the Student's t-test. The lunge, dead lift, and kettle swings were low intensity (<50% MVIC) and all showed higher EMG activity for semitendinosus than for biceps femoris. Bridge was low but approaching medium intensity, and the TRX, hamstring bridge, and hamstring curl were all medium intensity exercises (≥50% or <80% MVIC). The Nordic, fitball, and slide leg exercises were all high intensity exercises. Only the fitball exercise showed higher EMG activity in the biceps femoris compared with the semitendinosus. Only lunge and kettle swings showed peak EMG in the muscle-tendon unit lengthening phase and both these exercises involved faster speed. Some exercises selectively activated the lateral and medial distal hamstrings. Low, medium, and high intensity exercises were demonstrated. This information enables the clinician, strength and conditioning coach and physiotherapist to better understand intensity- and muscle-specific activation during hamstring muscle rehabilitation. Therefore, these results may help in designing progressive strengthening and rehabilitation and prevention programs.
... Although compound exercises involve extension of the hip, knee, and ankle joints, the lengthtension relationships do not appear to be favorable for promoting hypertrophy in the hamstrings and calves. Indeed, research indicates substantially higher EMG amplitudes when performing the leg curl and stiff leg deadlift (SJ exercises) versus the squat and leg press (MJ exercise) (2,41). Furthermore, hamstrings growth during regimented squat training is negligible (5,23,39), indicating that SJ exercise is requisite to hypertrophy this muscle complex. ...
Article
We performed a systematic review and meta-analysis comparing the effects of single-joint (SJ) and multijoint (MJ) resistance exercises on muscle hypertrophy of the limb muscles. A systematic search was performed to identify randomized trials that directly compared hypertrophic changes between SJ and MJ resistance exercises, as well as combinations of the 2, in healthy adults. A total of 7 studies met inclusion criteria, comprising 10 nested comparisons. Meta-analysis indicated a trivial standardized point estimate with a relatively moderate precision for the confidence interval estimate. Subgroup analyses showed no effect on results when stratifying studies according to combined SJ + MJ versus MJ training alone, as well as under volume-equated or nonequated conditions. However, scrutiny of individual studies in conjunction with related indirect evidence collectively indicate that SJ exercise may provide the ability to preferentially hypertrophy muscular subdivisions, potentially promoting more complete muscle development. We conclude that current evidence indicates similar whole muscle hypertrophy between MJ and SJ training. There may be added benefit to combining SJ and MJ exercises for targeting individual aspects of a given muscle, although this hypothesis remains understudied. Future studies are needed to explore the effects of SJ and MJ exercises in resistance training on regional muscle hypertrophy.
... During GS, the antagonistic muscles may have a significant influence on the stability of the weakened joints due to the agonist muscle co-activation [10]. However, the hamstring muscles showed weaker muscle activation during GS because these muscles are biarticular structure [11] and some researches show that weight bearing back squat training does not provide a sufficient stimulus for hamstring muscles [12,13]. Additionally, GS can increase pressure and stress on the lumbar spine [14] and could lead to an increase in spinal injuries [15]. ...
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Background Knee injuries in the lower limbs frequently occur, and lower limb muscles need to be strengthened to reduce injuries. Activating muscles can help strengthen muscles.. This study aimed to determine the squat exercises [general squat (GS), wall squat (WS), and Spanish squat (SS)] that effectively increased muscle activity using electromyography (EMG). Methods In this cross-sectional study, 22 participants performed three different squat exercises with EMG attached to the rectus femoris (RF), vastus lateralis (VL), vastus medialis, biceps femoris, semitendinosus, and semimembranosus. The Kruskal–Wallis H test was used to compare thigh muscle activities among the various squat exercises. Results During SS, RF showed greater muscle activation compared to WS and GS (RF: χ2 = 21.523, p = 0.000, η ² = 0.333). VL also showed greater muscle activation during SS compared to WS (VL: χ2 = 7.101, p = 0.029, η ² = 0.109). Conclusions The results from this study indicate that SS shows more activation in the RF and VL muscles compared to GS and WS. These findings suggest that SS can provide more muscle activation for the RF and VL muscles and will greatly help those who lack muscle activation in these muscles.
... Because of the biarticular nature of these muscles, their efficiency in hip extension movements, as seen in the squat, depends on the position of the knee. Thus, when the knees are flexed, these muscles are stretched near the hip but shortened at distal portions, and their capacity to extend the hip is then reduced (39,52). In this way, the hamstring muscles are posited to present null or reduced activation in the squat, especially in relation to the quadriceps (33,35). ...
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The squat is one of the most widely used exercises in resistance-training programs. The aim of the present narrative review was to analyze the effect of the squat on lower-limb muscle hypertrophy. Briefly, the available literature indicates that the squat is an effective exercise for inducing hypertrophy of the quadriceps, mainly the vastii, but also the rectus femoris, although to a reduced magnitude. Multiple lines of evidence suggest little to no hamstring hypertrophy from the back squat. While the gluteus maximus clearly participates mechanically in the back squat, few longitudinal studies exist on the topic. The limited evidence available on this topic suggests deeper squats may be more hypertrophic for the gluteus maximus, and that squat depth beyond 90 degrees of knee flexion may not provide further hypertrophy of the knee flexors. Despite the popularity of the many squat variations, there are still controversies surrounding their hypertrophic potential for lower-limb musculature. Further studies are needed to investigate the hypertrophic effects of different squat variations, as well as differences in hypertrophy due to squat depth, stance, barbell position, and different squat apparatuses/machines.
... The hamstrings present similar issues with respect to exercise selection. Although the hamstring muscles are activated in the squat, their EMG amplitude is only approximately half that achieved when performing single-joint exercises such as the stiff-leg deadlift and knee curl 16 . As with the rectus femoris, the attenuated activation of the hamstrings during squatting occurs due to the biarticular nature of the muscle complex, whereby its length remains relatively constant during exercise performance. ...
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Manipulation of resistance training variables has been shown to have a substantial effect on muscular adaptations. A major variable in this process is exercise selection. In addition to the effectiveness of a given exercise to recruit the target muscle groups, safety considerations and individual comfort during execution of a lift should be considered. The correct biomechanics of the chosen exercise will assist in promoting desired muscle adaptations, while proper safety procedures will reduce risk of injury. Lifting comfort will facilitate enjoyment and foster adherence to the program. Therefore, the purpose of this paper was to offer guidelines for selection of resistance training exercises based on the Efficiency, Safety, and Comfort Analysis Method (ESCAM).
... The electrical activity of the muscles is experimentally shown to be linearly dependent upon the velocity of eccentric and concentric contractions (Bigland & Lippold, 1954). As compared to other exercises, the concentric part of the muscle movement for leg curl is significant in the electromyography activity (Wright et al., 1999). Leg curl (hamstring curl) is an isolation workout which activates the muscle fibers primarily of hamstring muscle. ...
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The force experienced by the hamstring during the leg curl has been numerically investigated using the conservation theorem. The center of the meniscus is assumed to be the pivot point along with the uniform distribution of forces in the frictionless environment. The variation of force experienced by the hamstring during the concentric motion of the leg curl has been derived and graphically illustrated. It is found that the force experienced by the hamstring increases with the increase in length of the lower leg and its weight as well. The magnitude of force decreases with the increase in distance from the pivot to insertion. However, the magnitude of force increases from about 3.60 to 4.79 kN in the practically valid region 3 to 4 cm distance from the pivot to insertion with the increase in weight of lower leg from 5 to 15 kg. On the other hand, the magnitude of force increases from about 3.75 to 9.80 kN with the increase in weight suspended on the machine from 10 to 40 kg. In addition, the force decreases with the increase in upper leg dimension, but it linearly increases with the increase in the angle of suspension.
... This type of DS-AMSS warm-up may not be suitable for multi-joint movements where both the anterior and posterior chain musculatures are being recruited such as in barbell squats. This is due to the method of action being to decrease muscular tension, stiffness, and electrical activity of the opposing muscle group (the hamstrings) which acts as a hip extensor and knee flexor in a multi-joint exercise such as a back squat (Wright et al., 1999). Single joint exercises or exercise sessions where a singular muscle group is trained such as the quadriceps are most suitable to a DS-AMSS warm up. ...
Article
Antagonist static-stretching and dynamic-stretching are both effective at improving muscular performance. The purpose of this study was to investigate responses to a dynamic stretching warm-up protocol, a static-stretching warm-up protocol and a combined dynamic-stretching and antagonist static stretching warm-up protocol on iso-kinetic leg extension performance. Twelve participants completed a baseline (PRE) isokinetic knee-extension test at 60°.s −1 and 300°.s −1 , following a 5 min warm-up on a cycle ergometer. Subsequently, participants completed the following warm-up protocols randomly over a three-week period: dynamic-stretching (DS); antagonist muscle static-stretching (AMSS) and dynamic followed by antagonist muscle static-stretching (DS-AMSS). A repeated measures analysis of variance (ANOVA) was conducted to determine where significant differences existed for peak torque, total work, average power, time-to-peak-torque and relative peak torque between warm-up protocols. DS-AMSS facilitated a significantly higher peak torque and total work compared to PRE, DS and AMSS at 60°.s −1 and 300°.s −1 P < 0.05, respectively). DS-AMSS caused significantly greater relative peak torque than PRE for 60°.s −1 and 300°.s −1 (P < 0.05). DS-AMSS resulted in significantly reduced time-to-peak-torque and increased average power at 60°.s −1 compared to PRE, DS and AMSS (P < 0.05). DS-AMSS and AMSS resulted in a significant reduction in time-to-peak-torque and increased average power compared to the PRE and DS (P < 0.05) at 300°.s −1 .
... Some studies did not normalize [44] or did so by expressing themselves as a percentage contribution to the total electrical activity of all the muscles tested [30]. Other studies used the highest integrated EMG value among the concentric and eccentric contractions of all exercises, noting that the normalized peak EMG data follow a trend similar to the integrated data [49]. Other authors have used the total activity of each of the muscles (total activity of the quadriceps and the hamstrings) to normalize the signal from each muscular belly [30]. ...
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(1) Background: this study aimed to determine if there are differences in quadriceps and hamstring muscle activation in professional male and female soccer players. (2) Methods: muscle activation was recorded by surface electromyography in 27 professional soccer players (19 male and 8 female). The players performed the Bulgarian squat and lunge exercises. Vastus medialis, vastus lateralis, rectus femoris, semitendinosus, and biceps femoris were the muscles analyzed. (3) Results: The statistical analysis of the hamstring:quadriceps ratio showed no significant differences (p > 0.05). Significant differences were found in the vastus medialis:vastus lateralis ratio for both the lunge exercise (t20 = 3.35; p = 0.001; d = 1.42) and the Bulgarian squat (t23 = 4.15; p < 0.001; d = 1.76). For the intragroup muscular pattern in the lunge and Bulgarian squat exercises, the female players showed higher activation for the vastus lateralis muscle (p < 0.001) than the male players and lower muscle activation in the vastus medialis. No significant differences were found in the rectus femoris, biceps remoris, and semitendinosus muscles (p > 0.05). (4) Conclusions: Differences were found in the medial ratio (vastus medialis: vastus lateralis). Moreover, regarding the intramuscular pattern, very consistent patterns have been found. In the quadriceps muscle: VM>VL>RF; in the hamstring muscle: ST>BF. These patterns could be very useful in the recovery process from an injury to return players to their highest performance.
... Although the single-joint MVC techniques are the most prevalent in the literature, other techniques have been used. These methods include normalizing muscle activity to the peak value of a maximal or submaximal effort of the same task (9,25); mean value of the dynamic task (4); peak value of the dynamic task (30); peak value during several repetitions of an exercise (27); averaging peak values during the first repetition of a series of repetitions (Rep1%) for a resistance exercise (15,17); and peak value during a 1-repetition maximum (1RM) of a resistance training exercise (18,23). Ball and Scurr have suggested that EMG normalization should include normalization tasks that are similar to the movement under investigation, and ones that are familiar among testing participants (2). ...
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International Journal of Exercise Science 13(1): 1098-1107, 2020. Currently, no gold standard electromyography (EMG) normalizing technique exists when conducting between-muscle comparisons of muscle activity during isotonic resistance training exercises. The aim of this study was to assess if between-muscle activation during the back-squat differed among electromyography (EMG) normalization techniques when normalizing to: (1) 1 repetition maximum (1RM), (2) maximal voluntary isometric contraction (MVIC), and (3) the first of a set of three repetitions (Rep1%) in trained female lifters. Thirteen participants completed a back-squat 1RM, MVIC of the rectus-femoris (RF) and gluteus-maximus (GM), and three repetitions of the back-squat at 80% 1RM. For the 1RM and MVIC normalization techniques, the average of the peak RMS signal of both muscles during the three submaximal reps were normalized to the peak 1RM and MVIC signals. The Rep1% averaged the peak RMS signals of both muscles during the 2 nd and 3 rd submaximal repetitions normalized to the peak signal during the 1 st repetition. The RF-GM between-muscle EMG (ΔEMG) differed among normalization techniques (p < 0.001, ηp 2 = 0.48). Post-hoc pairwise comparisons indicated MVIC normalization elicited different ΔEMG with large effects compared to both 1RM (p = 0.037; d = 1.2) and Rep1% (p = 0.004; d = 1.9) techniques, but the 1RM and Rep1% did not produce different ΔEMG (p = 0.27; d = 0.8). Our findings suggest EMG normalization technique influences the magnitude and direction of between-muscle activation during common lifting exercises, and we recommend normalizing isotonic movements to dynamic normalization methods such as a 1RM or Rep1%.
... Although the single-joint MVC techniques are the most prevalent in the literature, other techniques have been used. These methods include normalizing muscle activity to the peak value of a maximal or submaximal effort of the same task (9,25); mean value of the dynamic task (4); peak value of the dynamic task (30); peak value during several repetitions of an exercise (27); averaging peak values during the first repetition of a series of repetitions (Rep1%) for a resistance exercise (15,17); and peak value during a 1-repetition maximum (1RM) of a resistance training exercise (18,23). Ball and Scurr have suggested that EMG normalization should include normalization tasks that are similar to the movement under investigation, and ones that are familiar among testing participants (2). ...
... EMG activity depends on multiple factors, such as length of the muscle, number of the joints involved in the exercise [27][28][29] , configuration of the training load 6,30 and subject´s training status. Under a high force requirement the neuromuscular system would demand a recruitment of MU close to maximal, however, for the submaximal efforts it is possible that this recruitment occurs in a different manner, depending on the situation and even on the subject, with the purpose of maintaining the efficiency of the task. ...
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This study investigate the effect of 10-week strenght training on the amplitude of the electromyographic (EMG) signal of vastus medialis, vastus lateralis and rectus Femoris. Twenty three untrained volunteers performed 3-5 sets (3 sets-weeks 1 and 2; 4 series-weeks 3 and 4; 5 series weeks 5 to 10) with 6 repetitions, intensity of 50% of 1 repetition maximum (1RM), 3 min rest between sets and 6 s repetition duration at the knee extensor exercise. One group (5:1) performed concentric action of 5 s and eccentric of 1 s and the other (3:3) performed concentric of 3 s and eccentric of 3 s. The VM, VL and RF EMG (RMS) activities were recorded in each repetition of the three series at the first training session and the first three series at the last session. The protocol 5:1 led to EMG reduction in all portions, with a greater number of repetitions presenting differences at the VL and RF. VM and RF presented similar results at Group 3:3. It was verified that all the differences occurred in the second half of the series. It was also verified differences in EMG ratios just in group 3:3 and only in VM/ VL and VM/RF. These results suggest that the coordination was not affected when equivalent repetitions of series were compared. It was also suggested that these results were influenced by the reduced degrees of freedom of the exercise and the training load progression adopted. Resumo-Este estudo investigou o efeito de 10 semanas de treinamento de força na resposta eletro-miográfica (EMG) do vasto medial, vasto lateral e reto femoral. 23 voluntárias executaram 3 a 5 séries de 6 repetições, intensidade de 50% de 1 repetição máxima (RM), 3 minutos de pausa entre as séries e duração da repetição de 6 s no exercício extensor de joelhos. Um grupo (5:1) realizou a duração da ação concêntrica em 5 s e excêntrica em 1s e outro grupo (3:3) realizou a concêntrica em 3s e a excêntrica em 3s. A atividades EMG (RMS) destas três porções do quadríceps foram registradas em cada repetição das 3 séries da primeira sessão de treinamento e nas três primeiras séries da última sessão. Os resultados mostraram diferenças na metade final das séries, sendo que no grupo 5:1 houve redução na EMG em todas as porções e o VL e o RF mostraram redução em um número maior de repetições. No grupo 3:3 o VM e o RF apresentaram redução. Para as relações de ativação entre as porções, diferenças foram identificadas apenas no grupo 3:3 nas relações VM/VL e VM/RF em um número reduzido de repetições. Estes resultados apontam que a coordenação entre as porções sofreu poucas alterações quando comparadas as repetições equivalentes de cada série. Sugere-se que os reduzidos graus de liberdade do movimento utilizado e a progressão da carga de treinamento tenham sido os fatores que conduziram a este resultado
... The primary movers during a hexbar RDL are the hamstrings group (biceps femoris, semitendinosus, and semimembranosus) and gluteals (maximus, medius, and minimus). Stabilizers, which include musculature of the trunk and spine (rectus abdominis, internal and external obliques, transverse abdominis, and erector spinae group), work isometrically to brace the spinal column and ensure that no spinal flexion or extension occurs (8,14,21). ...
... The RMS values (Root Mean Square) obtained for each muscle and protocol were normalized to the peak value obtained in each bench press mode (PM, AD, TB and BB), so that the signal intensity was presented as a percentage of the peak activity. 13 The study was a randomized crossover design. The subjects attend a total of ten sessions. ...
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Objective: The purpose of this study was to examine the effect of pre-fatiguing the triceps brachii on subsequent strength performance and myoelectric activity in the barbell, dumbbell, and Smith machine bench press. Method: Nineteen trained men participated of this study (27.9 ± 4.5 years; 1.72 ± 0.1 m; 80.3 ± 9.2 kg). Ten-repetition maximum loads were determined for the triceps extension as well as the barbell barbell, dumbbell and Smith machine bench press. Three experimental protocols were performed in a randomized design. All experimental protocols began with four sets of the triceps extension (performed with a high pulley) to repetition failure followed by four sets to repetition failure for one of three bench press modalities. Two minute-rest intervals were adopted between sets and exercises. Total repetitions (work), training volume and myoelectric activity of pectoralis major, anterior deltoid, biceps brachii, and triceps brachii were recorded during each bench press modality. Results: Significantly greater activity of the biceps brachii was observed during performance of the dumbbell bench press versus barbell and Smith machine bench press. No other significant differences were observed between protocols. Conclusion: Therefore, considering the training volume and myoelectric activity of the synergistic muscles, similar performance across bench press modalities can be expected when preceded by performance of a triceps extension.
... The present study showed no significant differences of EMG reading on bicep femoris between three types of stance-width used. The activation of hamstring during RDL could be caused by the movement of knee where it was slightly bent while the hip joint was extending and the movement of trunk that lean forward during the exercise [15]. Knee joint angle also play an important role in the activation of quadriceps. ...
Article
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This study was conducted to determine the effect of different stance-width; i) narrow, ii) shoulder and iii) wide, on muscle activation and performance during Romanian deadlift (RDL) exercise. Thirty recreationally resistance trained men aged of 19-23 years old (22.20±1.13) were involved in this study. The participants need to perform RDL with 80% of their 1RM in three sessions with three difference stances in randomized order. To measure the muscle activation level during performing the exercise, the electromyogram (EMG) marker was placed on vastus lateralis, biceps femoris, gluteus maximus and multifidus muscles. The number of repetitions completed during each sets was recorded as indicator for performance. The mean EMG value during concentric and eccentric movement along with the number of repetitions completed were analysed using one way repeated measure analysis of variances (ANOVA). The result showed no significant differences were found on EMG reading of vastus lateralis and bicep femoris during eccentric and concentric phase of RDL when three different stances were used. However, when wide stances were used, a significant difference was observed on gluteus maximus whilst significant differences on multifidus were obviously seen when narrow stance were used. Higher number of repetition completed was significantly found when wide and shoulder width stances were used compared to narrow stance. The results of this study revealed the importance to choose correct stance width (depending on training objective) while performing RDL due to its effects on the muscle activation and performance.
... It is likely that as the quadriceps fatigued the hamstrings would have been activated to a greater degree to resist forces about the knee joint; as the hamstrings function to support the ACL in resisting antero-posterior forces [1]. Squatting exercises have been shown to activate the hamstrings significantly less than other hamstring exercises [47] and the squat position adopted for much of the exercise intervention during the current study may have prevented excessive loads being applied to the hamstrings; the low demand therefore likely insufficient to induce fatigue. Furthermore, when the participants performed the isokinetic knee flexions, the resistive force of the knee extensors was diminished due to their fatigued state and potential reduction in neural drive. ...
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Study aim : With contrary evidence regarding the effectiveness of acute whole-body vibration training (WBVT) on sporting performance, the current study examined WBVT’s effect on concentric torque of the quadriceps (Q) and hamstrings (H). Material and methods : Following ethical approval, 11 male team sport players (age: 22.9 ± 3.3 yrs, height: 1.80 ± 0.07 m, mass: 82.5 ± 12.6 kg) completed three separate weekly WBVT sessions. Baseline and post – WBVT intervention measurements of Q and H concentric torque were recorded, using an isokinetic dynamometer, at each session. Isokinetic knee extension and flexion was performed at 180 o s ⁻¹ through 90o range of motion. For the training intervention, vibration amplitude remained at 2 mm, while frequency was set at 0Hz, 30Hz or 50 Hz; randomised so participants experienced one frequency per session. Torque data (Nm) and H and Q ratio (H: Q) were analysed using 3-way and 2-way ANOVA with repeated measures respectively, with three within subjects’ factors: frequency, muscle group and intervention. Results : Main interaction effect (frequency x muscle group x intervention) was insignificant ( P = 0.327). Significant muscle group x frequency ( P = 0.029) and muscle group x intervention ( P = 0.001) interactions were found. Intervention, regardless of WBVT, significantly increased concentric torque of H ( P = 0.003) and significantly reduced concentric torque of Q ( P = 0.031). While H: Q x frequency interaction was insignificant ( P = 0.262), the intervention significantly improved H: Q ( P = 0.001). Conclusions : Team sport athletes experience a muscle-specific response in peak concentric torque to lower-body exercise. Acute WBVT does not provide additional positive or negative effects on Q or H strength.
... Researchers have found a strong correlation (r = 0.74) between the 1 RM back squat and 15 m swimming performance(West et al., 2011).Bishop et al. (2013) stated that the back squat and deadlift provide the necessary foundation for developing the gluteal complex and quadriceps. Deadlifts were ranked as the fifth most transferable dry-land resistance exercise with squats and deadlifts working as antagonist pairs of the lower body(Clark et al., 2012, Wright et al., 1999. Other exercises reported include; (1) core exercises, (2) Olympic lifts, (3) plyometrics and ...
Thesis
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Swimming performance requires a whole body coordinated movement to elicit high propulsive forces with the majority of forces produced from the upper body musculature. The current academic literature highlights a range of dry-land resistance exercises that show moderate to strong correlations to swimming performance; however, association does not imply causation. Specificity states that adaptations are specific to the nature of the training stress applied and therefore it is important to highlight the dry-land resistance exercises improving swimming performance. The aim of this research study is to examine the specificity of dry-land resistance exercises to swimming performance. A systematic review of the impact of resistance training on front crawl swimming performance highlighted that low volume, high force, traditional resistance training programmes, showed positive improvement in swimming performance. Neuromuscular adaptations contribute to resistance training exercises improving swimming performance according to several research studies. A review of the specificity between front crawl swimming and dry-land resistance exercises using electromyography (EMG) data highlighted a series of similar prime movers (i.e. latissimus dorsi, pectoralis major, triceps brachii and deltoids) between a range of dry-land resistance exercises. A qualitative study of elite swimming strength and conditioning coaches identified the dry-land resistance exercises most commonly used and deemed most relevant by practitioners and coaches. The bench press and pull up were the two upper body dry-land resistance exercises that coaches ranked highest in terms of improving swimming performance. This prompted an investigation of the specificity of these dry-land resistance exercises to front crawl swimming using EMG data analysis. Following a series of pilot tests, 14 male national and international swimmers were recorded using 2D kinematic analysis to identify event cycles and EMG to investigate muscle activations. The specificity of front crawl swimming to bench press and pull up exercises were examined using temporal coordination , temporal muscle activation overlaps, Functional Data Analysis (FDA) Pearson pointwise correlations, Statistical Parametric Mapping (SPM) t-tests and Root Mean Square Difference (RMSD). The findings of this research show that while the key prime movers between the bench press and pull up exercises and front crawl swimming are similar, there is limited specificity. The results would also suggest that these exercises are applicable for the general preparation period but not for the specific competition period. The large variability within the data set makes findings difficult to interpret. Future research needs to focus on individual analysis of specificity, as the large variability does not make group analysis techniques representative of the high level of individual variability found within the data set. Greater specificity is required through the development of a coherent biomechanical model of specificity that describes joint angles, angular velocity, torque and muscle activations.
... The gluteus maximus and hamstrings are primary hip extensor muscles. Although the gluteus maximus is adequately targeted in closed kinetic chain exercise such as the squat and leg press [32,37], the hamstrings are only moderately activated in these exercises [22,47], resulting in an imbalanced development between the quadriceps and hamstring muscles [32,37,48,49]. Illera-Domínguez et al. [48] observed that, after 4 weeks of squats, there was a 9.8% increase in the vastus medialis, 8.8% in the vastus medialis and lateralis, and 4.7% in the rectus femoris muscles; however, there was no statistically significant increase for any of the hamstring muscles. ...
Article
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Resistance training has been widely recommended as a strategy to enhance the functional autonomy and quality of life in older individuals. Among the variables that comprise a training session, the selection of exercises stands out as an important consideration for the elderly. Although a wide range of resistance exercise options exists, current guidelines generally do not indicate which exercises should be included and which muscles should be prioritized when prescribing training for older individuals. Therefore, given the lack of evidence-based information on the topic, this paper endeavors to establish recommendations to help guide the prescription of resistance exercises for older adults.
... For example, studies show that hamstrings EMG amplitude is significantly and markedly (~twofold) lower than that of the quadriceps during performance of the squat [23,24] and the leg press [25,26]. Moreover, EMG amplitudes have been found to be substantially greater when performing SJ exercise that directly targets the hamstrings (i.e., leg curl, stiff leg deadlift) compared to MJ lower-body exercise (i.e., squat, leg press) [27,28]. These data have a logical rationale from a functional anatomical perspective given that the hamstring muscles act as prime movers in both a hip extension and knee flexion, which in turn suggests its length would remain relatively constant during MJ lower-body exercise [29]. ...
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Resistance training volume, determined by the number of sets performed (set-volume) is considered one of the key variables in promoting muscle hypertrophy. To better guide resistance exercise prescription for weekly per-muscle training volume, the purpose of this paper is to provide evidence-based considerations for set-volume ratios between multi-joint (MJ) and single-joint (SJ) exercises so that practitioners can better manage prescription of training volume in program design. We analyzed this topic from three primary areas of focus: (1) biomechanical and physiological factors; (2) acute research; and (3) longitudinal research. From a biomechanical and physiological standpoint, when considering force production of different muscle groups, the moment arm of a given muscle, “motor abundance”, the link between biomechanics and exercise-induced fatigue, as well as the amount of time in voluntary muscle activation, a logical rationale can be made for SJ exercises producing greater hypertrophy of the limb muscles than MJ exercises (at least from specific exercises and under certain conditions). This would mean that sets for a MJ exercise should be counted fractionally for select muscles compared to an SJ exercise (i.e., less than a 1:1 ratio) when prescribing set-volumes for given muscles. When considering results from acute studies that measured muscle activation during the performance of SJ and MJ exercises, it seems that MJ exercises are not sufficient to maximize muscle activation of specific muscles. For example, during performance of the leg press and squat, muscle activation of the hamstrings is markedly lower than that of the quadriceps. These results suggest that a 1:1 ratio cannot be assumed. Current longitudinal research comparing the effects of training with MJ vs. SJ or MJ + SJ exercises is limited to the elbow flexors and the evidence is somewhat conflicting. Until more research is conducted to derive stronger conclusions on the topic, we propose the best advice would be to view set-volume prescription on a 1:1 basis, and then use logical rationale and personal expertise to make determinations on program design. Future research should focus on investigating longitudinal hypertrophic changes between MJ and SJ in a variety of populations, particularly resistance-trained individuals, while using site-specific measures of muscle growth to more systematically and precisely compute effective individualized set-volumes.
... As a reason for the weaker activation of the hamstring muscles during squat exercises, Sugisaki et al. (2014) indicated that there was no change in the lengths of the hamstring muscles, and, thus, these muscles contract almost isometrically. Other researchers also indicated that squat training did not provide a sufficient training stimulus for the hamstring muscles (Ebben 2009;Wright et al. 1999). Bloomquist et al. (2013) showed that the crosssectional area of the hamstring muscles did not change after 12 weeks of full and shallow squat training. ...
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Purpose The purpose of this study was to compare the effects of squat training with different depths on lower limb muscle volumes. Methods Seventeen males were randomly assigned to a full squat training group (FST, n = 8) or half squat training group (HST, n = 9). They completed 10 weeks (2 days per week) of squat training. The muscle volumes (by magnetic resonance imaging) of the knee extensor, hamstring, adductor, and gluteus maximus muscles and the one repetition maximum (1RM) of full and half squats were measured before and after training. Results The relative increase in 1RM of full squat was significantly greater in FST (31.8 ± 14.9%) than in HST (11.3 ± 8.6%) (p = 0.003), whereas there was no difference in the relative increase in 1RM of half squat between FST (24.2 ± 7.1%) and HST (32.0 ± 12.1%) (p = 0.132). The volumes of knee extensor muscles significantly increased by 4.9 ± 2.6% in FST (p < 0.001) and 4.6 ± 3.1% in HST (p = 0.003), whereas that of rectus femoris and hamstring muscles did not change in either group. The volumes of adductor and gluteus maximus muscles significantly increased in FST (6.2 ± 2.6% and 6.7 ± 3.5%) and HST (2.7 ± 3.1% and 2.2 ± 2.6%). In addition, relative increases in adductor (p = 0.026) and gluteus maximus (p = 0.008) muscle volumes were significantly greater in FST than in HST. Conclusion The results suggest that full squat training is more effective for developing the lower limb muscles excluding the rectus femoris and hamstring muscles.
... The SEMG values were determined by an average of the SEMG values of 3 central repetitions of each set. Normalization was performed using the highest peak SEMG value (24). ...
... With respect to exercise interventions, the squat offers one opportunity to target the capacity of the gluteus maximus and the adductors (Pereira et al., 2010). In contrast to these mono-articular synergists, the BFlh is only moderately active during the squat (Aspe and Swinton, 2014;Ebben et al., 2000;Schoenfeld, 2010), due to the small net change in this hamstring's length during the coupled hip and knee actions (Wright et al., 1999). A deeper squat, performed with a wider foot placement places further bias upon the gluteus maximus (Caterisano et al., 2002;Paoli et al., 2009), and the adductors (Pereira et al., 2010), in respect to other lower limb synergists. ...
Article
A synergistic algebra appears to be at play in the body, sustaining an athlete's performance in the face of competing demands, yet these may be associated with risk. Akin to the employment of redundancy within engineering sciences, we suggest this phenomenon can be strategically harnessed through careful consideration of programme scheduling, contraction profiles and exercise design to share the work amongst other tissues and access the plasticity evident within the movement system. Tabled 1 SynergistsPrimary Focus Biceps Femoris Long Head, Semimembranosus Sagittal plane, eccentric force production, fascicle elongation Semitendinosus, Biceps Femoris Short Head, Popliteus Sagittal and transverse plane fatigue tolerance Gluteus Maximus Sagittal plane, concentric force production and fascicle shortening Adductor Magnus Tri-planar eccentric force production, fascicle elongation Gastrocnemius Increased stiffness facilitating enhanced force transfer and tendon contribution Oblique abdominals Tri-planar eccentric force production within small amplitudes of muscle length around lumbo-pelvic neutral alignment Specific muscles in the management of hamstring injuries for repeat sprint athletes (footballers). • Open table in a new tab
... With respect to exercise interventions, the squat offers one opportunity to target the capacity of the gluteus maximus and the adductors (Pereira et al., 2010). In contrast to these mono-articular synergists, the BFlh is only moderately active during the squat (Aspe & Swinton, 2014;Ebben et al., 2000;Schoenfeld, 2010), due to the small net change in this hamstring's length during the coupled hip and knee actions (Wright et al., 1999). A deeper squat, performed with a wider foot placement places further bias upon the gluteus maximus (Caterisano et al., 2002;Paoli et al., 2009) One caveat to the use of the squat or any exercise seen to increase the force production of the quadriceps is the association between increased HSI risk and the ratio of concentric quadriceps to eccentric hamstring force production (Crosier, 2004;Orchard, 2001;Petersen & Holmich, 2005). ...
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... Bishop et al. (3) stated that the back squat and deadlift provide the necessary foundation for developing the gluteal complex and quadriceps. Deadlifts were ranked as the fifth most transferable dry-land RT training exercise with squats and deadlifts working as antagonist pairs of the lower body (6,45). ...
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Crowley, E, Harrison, AJ, and Lyons, M. Dry-land resistance training practices of elite swimming strength and conditioning coaches. J Strength Cond Res 32(9): 2592-2600, 2018-No research to date has investigated dry-land resistance (RT) training practices of elite swimming strength and conditioning coaches. This is the first comprehensive study exploring dry-land RT training practices in swimming. The aims of this study were to examine (a) the dry-land RT training practices and exercises used by elite swimming strength and conditioning coaches and (b) the rationale provided by coaches about their practices and prescription of specific dry-land RT training exercises. Twenty-three (n = 21 males, n = 2 females) elite swimming strength and conditioning coaches, from Ireland (n = 7), Great Britain (n = 5), Australia (n = 6), and the United States of America (n = 5) were recruited through their specific national governing bodies. Coaches completed an online questionnaire consisting of 7 sections; subject information, informed consent, coach's biography, coach education, current training commitments, dry-land RT training practices and exercises, and additional information. The results showed that coaches had varying levels of experience, education and worked with different level swimmers. A total of 95 dry-land RT training exercises were used by the coaches across 4 different dry-land RT training practices (warm-up, circuit training, traditional RT training and plyometrics). Traditional RT training (87%) was the most commonly practiced. The pull-up and squat were the most popular dry-land RT training exercises used by elite swimming strength and conditioning coaches. Future research needs to focus on exploring the specificity and the transfer of RT training exercises to swimming performance.
... For proper comparisons, the RMS value (Root Mean Square) obtained for each muscle (pectoralis major, anterior deltoid, biceps brachii, and triceps brachii) was normalized to the peak values obtained relative to all exercise modes. The signal intensity was presented as a percentage of the peak (11). ...
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Pimentel I, A. Smith Machine vs. Barbell: Ten Repetition Maximum Loads and Muscle Activation Pattern during Upper Body Exercises. JEPonline 2016;19(5):86-92. The aim of this study was to investigate muscle activation performance and maximum repetition test for the bench press, military press and the close-grip bench press exercises with the barbell and the Smith Machine. Twelve recreationally trained men (mean ± SD: 21.83 ± 4.5 yrs; 1.72 ± 0.1 cm; 80.3 ± 9.2 kg; 25.1 ± 2.96 kg·m-2 ; 17.3 ± 6.85 %Fat) underwent a within-subject, randomized and counterbalanced repeated-measures to analyze the 10-RM strength and muscle activation in the bench press, military press, and the close-grip bench press. Electromyographic signals were collected for the pectoralis major, anterior deltoid, biceps brachii, and triceps brachii during 1 set of each exercise with the barbell and smith machine. No difference was observed in muscle activity for pectoralis major, anterior deltoid, biceps brachii, and triceps brachii when comparing the barbell and the Smith Machine (P>0.05). However, significant differences in 10-RM loads were observed between the barbell and the Smith Machine for the close-grip bench press and military press exercises. These finding should be important when considering the determination of training loads.
... The SEMG values were determined by an average of the SEMG values of 3 central repetitions of each set. Normalization was performed using the highest peak SEMG value (24). ...
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Farias, DdA, Willardson, JM, Paz, GA, Bezerra, EdS, and Miranda, H. Maximal strength performance and muscle activation for the bench press and triceps extension exercises adopting dumbbell, barbell and machine modalities over multiple sets. J Strength Cond Res 31(7): 1879-1887, 2017-The purpose of this study was to investigate muscle activation, total repetitions, and training volume for 3 bench press (BP) exercise modes (Smith machine [SMBP], barbell [BBP], and dumbbell [DBP]) that were followed by a triceps extension (TE) exercise. Nineteen trained men performed 3 testing protocols in random order, which included: (P1) SMBP + TE; (P2) BBP + TE; and (P3) DBP + TE. Each protocol involved 4 sets with a 10-repetition maximum (RM) load, immediately followed by a TE exercise that was also performed for 4 sets with a 10RM load. A 2-minute rest interval was adopted between sets and exercises. Surface electromyographic activity was assessed for the pectoralis major (PM), anterior deltoid (AD), biceps brachii (BB), and triceps brachii (TB). The results indicated that significantly higher total repetitions were achieved for the DBP (31.2 ± 3.2) vs. the BBP (27.8 ± 4.8). For the TE, significantly greater volume was achieved when this exercise was performed after the BBP (1,204.4 ± 249.4 kg) and DBP (1,216.8 ± 287.5 kg) vs. the SMBP (1,097.5 ± 193 kg). The DBP elicited significantly greater PM activity vs. the BBP. The SMBP elicited significantly greater AD activity vs. the BBP and DBP. During the different BP modes, the SMBP and BBP elicited significantly greater TB activity vs. the DBP. However, the DBP elicited significantly greater BB activity vs. the SMBP and BBP, respectively. During the succeeding TE exercise, significantly greater activity of the TB was observed when this exercise was performed after the BBP vs. the SMBP and DBP. Therefore, it seems that the variation in BP modes does influence both repetition performance and muscle activation patterns during the TE when these exercises are performed in succession.
... An eccentric muscle contraction occurs when the muscles actively lengthen in response to a greater opposing force. Some exercises that promote eccentric contractions include walking or running downhill (Chen, Nosaka, & Wu, 2008), lowering weights (Wright, Delong, & Gehlsen, 1999), Nordic hamstring exercise (Arnason, Andersen, Holme, Engebretsen, & Bahr, 2008) and cycling on an eccentric ergometer (Gross et al., 2010;LaStayo, Pierotti, Pifer, Hoppeler, & Lindstedt, 2000). It has been shown that eccentric cycling exerts a lower metabolic demand than concentric cycling when exercising at the same muscular work (Abbott, Bigland, & Ritchie, 1952;LaStayo, Ewy, Pierotti, Johns, & Lindstedt, 2003;Penailillo, Blazevich, Numazawa, & Nosaka, 2013). ...
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Methods: Eight sedentary men (23.3 ± 0.7 y) underwent two eccentric cycling sessions (EXT and FLEX) of 30 min each, at 60% of the maximum power output. Oxygen consumption (VO2), heart rate (HR) and rated perceived exertion (RPE) were measured during cycling. Countermovement and squat jumps (CMJ and SJ), muscle flexibility, muscle soreness and pain pressure threshold (PPT) of knee extensor and flexor muscles were measured before, immediately after and 1-4 days after cycling. Results: FLEX showed greater VO2 (+23%), HR (+14%) and RPE (+18%) than EXT. CMJ and SJ performance decreased similarly after cycling. Muscle soreness increased more after EXT than FLEX and PPT decreased in knee extensor muscles after EXT and decreased in knee flexor muscles after FLEX. Greater loss of muscle flexibility in knee flexor muscles after FLEX was observed. Conclusion: Eccentric cycling of knee flexor muscles is metabolically more demanding than that of knee extensors, however muscle damage induced is similar. Knee flexors experienced greater loss of muscle flexibility possibly due to increased muscle stiffness following eccentric contractions.
... In comparison with other strength exercises, such as the squat, the deadlift has received comparatively little research interest (2,4,5,9,11,13,19). A common belief is that the deadlift and back squat have similar movement patterns and that it is acceptable to relate theories and new findings between the 2 exercises. ...
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The deadlift exercise is commonly performed to develop strength and power, and to train the lower body and erector spinae muscle groups. However, little is known about the acute training effects of a hexagonal barbell vs. a straight barbell when performing deadlifts. Therefore, the purpose of this study was to examine the hexagonal barbell in comparison to the straight barbell by analyzing electromyography (EMG) from the vastus lateralis, biceps femoris, and erector spinae, as well as peak force, peak power, and peak velocity using a force plate. Twenty men, with deadlifting experience volunteered to participate in the study. All participants completed a one-repetition maximum (1RM) test with each barbell on two separate occasions. Three repetitions at 65% and 85% 1RM were performed with each barbell on a third visit. The results revealed there was no significant difference for 1RM values between the straight and hexagonal barbells (mean ± SD in kg = 181.4 ± 27.3 vs. 181.1 ± 27.6, respectively) (p > 0.05). Significantly greater normalized EMG values were found from the vastus lateralis for both the concentric (1.199 ± 0.22) and eccentric (0.879 ± 0.31) phases of the hexagonal barbell compared to the straight barbell deadlift (0.968 ± 0.22 and 0.559 ± 1.26), while the straight barbell deadlift led to significantly greater EMG values from the bicep femoris during the concentric phase (0.835 ± 0.19) and the erector spinae (0.753 ± 0.28) during the eccentric phase compared to the corresponding values for the hexagonal barbell deadlift (0.723 ± 0.20 and 0.614 ± 0.21) (p ≤ 0.05). In addition, the hexagonal barbell deadlift demonstrated significantly greater peak force (2,553.20 ± 371.52 N), peak power (1,871.15 ± 451.61 W), and peak velocity (0.805 ± 0.165) compared to the straight barbell deadlift values (2,509.90 ± 364.95 N, 1,639.70 ± 361.94 W, and 0.725 ± 0.138 m/s) (p ≤ 0.05). These results suggest that the barbells led to different patterns of muscle activation, and that the hexagonal barbell maybe more effective at developing maximal force, power, and velocity.
Article
BACKGROUND: An advantage that deadlift (DL) has over back squat (BSQ) is that the latter requires additional equipment (i.e., squat rack). Accordingly, if DL can lead to positive effects on jumping, acceleration, and change of direction, DL could present as a more practical training exercise than that of BSQ. OBJECTIVE: This study aimed to compare the effects of DL and BSQ on jumping, acceleration, and change of direction. METHODS: Twenty-three men (12 in the DL group [age: 20.3 ± 1.4 years old, height: 169.6 ± 6.7 cm, body weight: 65.7 ± 11.2 kg] and 11 in the BSQ group [age: 20.2 ± 1.9 years old, height: 171.5 ± 4.8 cm, body weight: 70.1 ± 6.8 kg]) participated in this study. The participants performed five repetitions maximum (RM) of DL and BSQ, and the isokinetic strength of hip joint extension, muscle thickness of the gluteus maximus and hamstrings, countermovement jump (CMJ) height, 10 m sprint time, and T-test results were measured. The 1RM was estimated using the 5RM and normalized to body weight (BW). Both groups performed supervised DL and BSQ training for eight sessions. RESULTS: There were significant improvements on 1RM DL/BW (p< 0.01), 1RM BSQ/BW (p< 0.01), and 10 m sprint (p< 0.01) in the two groups. The effect sizes (d) of the DL and BSQ groups were 2.01 and 1.04 for 1RM DL/BW, 1.08 and 2.08 for 1RM BSQ/BW, 0.35 and 0.11 for CMJ height, and -0.94 and -0.54 for 10 m sprint, respectively. CONCLUSIONS: DL training might improve jumping and acceleration compared to those of BSQ training.
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Foam rolling (FR) is a practice that has increased in popularity before and after resistance training. The purpose of this study was to compare the acute effects of different foam rolling periods for the lower body muscles on subsequent performance, myoelectric activity and rating of perceived exertion in trained men. Fourteen men (26.2 ± 3.2 years, 178 ± 0.04 cm, 82.2 ± 10 kg and body mass index 25.9 ± 3.3kg/m-2) volunteered for this study. Four repetition maximum (4-RM) loads were determined for hexagonal bar deadlift and 45°-angled leg press during test and retest sessions over two nonconsecutive days. The experimental conditions included a traditional protocol (TP) with no prior foam rolling, and four other conditions that involved FR applied to the quadriceps, hamstrings and triceps surae for one set of 30 sec (P1), two sets of 30 sec (P2), three sets of 30 sec (P3), or four sets of 30 sec (P4).The resistance training consisted of five sets with 4-RM loads. The number of repetitions completed, the myoelectric activity of lower limbs were recorded, as well as the rating of perceived exertion for each protocol. There were no differences between the protocols in the total repetitions for the hexagonal bar deadlift and 45° angled leg press exercises. Similar results between protocols were also noted for muscle activity and rated perceived exertion (RPE). Therefore, the results of the present study indicated that the FR didn't provide effects on performance, myoelectric activity and rating of perceived exertion responses during high intensity resistance performance for lower limb exercises.
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Resistance exercise has been widely recommended for elderly population, since this type of exercise induces important health benefits, especially to improve functional capacity and preserve muscle mass, thus reflecting on the quality of life of older individuals. Among the several components of the resistance exercises the selection of movements to be performed is one of the most important and must be carefully analyzed. Although there may be a wide range of options, the most important recommendations do not specifically indicate the movements that should be included and muscle groups that should be prioritized when prescribing resistance exercise for the elderly. Therefore, considering that there is a lack of information for the Physical Education professional about the topic, this study was developed to support the choices of the movements that will compose the resistance exercise program for the elderly. The study was carried out by compiling and analyzing assumptions and scientific evidences related to resistance exercises and needs of elderly individuals. In conclusion, the choice of movements should be based on the principles of kinesiology, the needs of the elderly, muscle action and exercise safety in order to obtain beneficial results for general health and attenuate possible risks.Keywords: Exercise. Aging. Physical Exertion.ResumoO exercício resistido vem sendo amplamente recomendado para população idosa, uma vez que esse tipo de exercício físico induz a importantes benefícios para saúde; sobretudo, no aprimoramento da capacidade funcional e na preservação da massa muscular, refletindo, desse modo, na qualidade de vida do indivíduo idoso. Dentre os diversos componentes dos exercícios resistidos, a seleção dos movimentos a serem executados é um dos mais importantes e deve ser cuidadosamente analisado. Embora possa existir vasta gama de opções, as principais recomendações não indicam especificamente os movimentos que devem ser incluídos e os grupos musculares que devem ser priorizados nos programas de exercícios resistidos. Portanto, considerando haver uma lacuna de informações sobre o tema, o estudo foi realizado com intuito de subsidiar a seleção dos movimentos que deverão compor os programas de exercícios resistidos para idosos. O estudo foi realizado mediante compilação e análise de pressupostos e evidências científicas referentes aos exercícios resistidos e as necessidades dos idosos. Concluiu-se que a seleção dos movimentos deve ser baseada nos princípios da cinesiologia, nas necessidades dos idosos, na ação muscular e na segurança de execução para se alcançar resultados benéficos para saúde em geral e atenuar possíveis riscos.Palavras-chave: Exercício. Envelhecimento. Esforço Físico.
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Context: Within each hamstring muscle, there are segments with separate nerve innervation. However, a better understanding of activation levels within these regions during resistance exercise could lead to region-specific training for improved performance and injury prevention. Objective: To compare muscle activation levels within regions of the hamstrings during various resistance exercises. Design: Within-subjects repeated measures. Setting: Biomechanics laboratory. Participants: Eighteen young adult females with previous competitive sport participation and resistance training experience. Intervention: One set of 3 repetitions with an 8RM load on the bilateral squat, modified single-leg squat, stiff-legged dead lift, and leg curl (LC). Main outcome measures: Normalized surface electromyography of 4 hamstring regions (proximal-medial, proximal-lateral, distal-medial, and distal-lateral). Results: For LC only, electromyography measures for the proximal-lateral location were significantly lower than for the distal-lateral, t18 = 5.6, P < .001, and proximal-medial, t18 = 2.4, P = .01 locations for concentric contractions. Similar results were observed for eccentric contractions. No other exercises revealed regional activation differences. When comparing the pooled proximal (medial and lateral) region across exercises, the LC demonstrated significantly greater activation than the modified single-leg squat, t18 = 5.20, P < .001, stiff-legged dead lift, t18 = 7.311, P < .001, and bilateral squat, F3,54 = 49.8, P < .001. Similar significantly greater levels were also found during the LC for the pooled distal, medial, and lateral regions. In addition, the modified single-leg squat electromyography was significantly greater at all regions in comparison with the stiff-legged dead lift and bilateral squat. Conclusions: The data did not reveal consistent regional differences within the different exercises included in this study. However, the data indicate that the LC produces the highest hamstring activation in all regions across exercises. Inclusion of single-joint knee-flexion exercises would appear to be most beneficial for hamstrings development in a resistance-training program.
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This study aimed to study the co-activation of hamstring-quadriceps muscles during submaximal strength exercises without the use of maximum voluntary isometric contraction testing and compare (i) the inter-limb differences in muscle activation, (ii) the intra-muscular group activation pattern, and (iii) the activation during different phases of the exercise. Muscle activation was recorded by surface electromyography of 19 elite male youth players. Participants performed five repetitions of the Bulgarian squat, lunge and the squat with an external load of 10 kg. Electrical activity was recorded for the rectus femoris, vastus medialis, vastus lateralis, biceps femoris and semitendinosus. No significant inter-limb differences were found (F1, 13=619; p=0.82; partial η2=0.045). Significant differences were found in the muscle activation between different muscles within the muscle group (quadriceps and hamstrings) for each of the exercises : Bulgarian squat (F1,18=331: p<0.001; partial η2=0.80), lunge (F4,72=114.5; p<0.001; partial η2=0.86) and squat (F1,16=247.31; p<0.001; partial η2=0.93).Differences were found between the concentric, isometric and eccentric phases of each of the exercises (F2, 26=52.27; p=0.02; partial η2=0.80). The existence of an activation pattern of each of the muscles in the three proposed exercises could be used for muscle assessment and as a tool for injury recovery.
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The back squat is the cornerstone of many strength and conditioning programs, with increases in back squat strength associated with improvements in athletic performance. a variety of back squat techniques have been described throughout the literature and can be observed on social media and in strength and conditioning facilities, with no current consensus regarding optimal technique. basedoncurrently available evidence, a full depth squat, with a natural foot position, approximately shoulder-width apart, with unrestricted anterior movement of the knees, an upright trunk, with a forward and upward gaze is recommended. these recommendations should permit individualization based on individual anthropometrics. for a video abstract of this article, see supplemental digital content 1 (See video, http://links.lww.com/scj/a241).
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A manipulação do volume e da densidade no treinamento de força é realizada através do gerenciamento do número de séries realizadas em cada grupamento muscular e como essas séries são alocadas na sessão e na semana de treinamento. A manipulação dessas variáveis altera as respostas agudas e as adaptações crônicas no sistema neuromuscular. Portanto, o objetivo deste trabalho foi revisar os efeitos agudos e adaptações neuromusculares decorrentes da manipulação diária e semanal do volume e densidade no treinamento de força. A combinação da ordem dos exercícios, sistemas de treinamentos e séries realizadas tem demonstrado ser uma estratégia eficiente para aumentar o desempenho e reduzir o tempo da sessão de treinamento. Estudos prévios sugerem que o aumento da sobrecarga pode ser realizado através da manipulação das séries na sessão do treinamento e do número de sessões ao longo da semana. Quanto à frequência de treinamento, a literatura parece ser clara ao sugerir ganhos superiores de força e hipertrofia muscular quando duas a três sessões por grupamento muscular são realizadas na semana. Entretanto, frequências de até 6 sessões na semana para o mesmo grupo muscular podem favorecer o anabolismo muscular. A presente revisão conclui que em uma única sessão de treinamento até 30 séries por grupo muscular podem ser necessárias dependendo do objetivo e da população treinada. O desempenho agudo da sessão (volume absoluto, força e potência) pode ser melhorado por meio de diferentes ordens de exercícios ou sistemas de treinamento quando essas estratégias aumentam o intervalo de recuperação entre séries e exercícios para o mesmo grupamento muscular. Adicionalmente, uma única sessão de treinamento por semana pode manter ou até mesmo aumentar a força e o tamanho muscular. Palavras-Chave: treinamento de força, volume relativo, volume absoluto, sessão de treinamento, frequência semanal. The manipulation of both volume and density on strength training is performed by managing the number of sets performed by each muscle group, and how its sets can be organized on a single-session and week of training. Its well known that this type of variable manipulation affect the acute effects and chronic adaptations of the neuromuscular system. Therefore, the aim of this work was to review the acute effects, and neuromuscular adaptations of the daily and weekly manipulation of volume and density during the resistance training. The combination of exercise order, training systems, and sets have shown to be an efficient strategy to improve performance and reduce the session time. Previous studies suggested that the progressive overload is attained by increasing the number of sets in a given strength session or by increasing the training frequency. Regarding the training frequency, the literature seems to be clear when suggests superior gains in strength and muscle hypertrophy when performed two to three sessions per week for each muscle group. However, up to 6 strength sessions for the same muscle group might boost muscle anabolism. The present review concludes that in a single session up to 30 sets per muscle group may be required depending on the goal and the population trained. The acute training performance (ie. absolute volume, force and power) may be enhanced by different exercise orders or training systems when its strategies increase the resting interval between sets or exercises for the same muscle group. Additionally, a single session of resistance training at week may be able to maintain or even promote strength and muscle size gains, howerver, two to three sessions have shown to be superior to promoting such neuromuscular adaptations.
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The purpose of the present study was to compare myoelectric activity of selected lower limb muscles during squat, leg press and hack squat exercises performed with different loads. Ten powerlifter males (age: 27 ± 4.85 yrs; height: 177 ± 5098 cm; weight: 80±12.13 kg) were participated in the study. Subjects performed all three exercises namely, squat, leg press and hack squat at 70% and 90% of their one-repetition maximum (1 RM). Surface electromyographic signals from peroneus longus, medial gastrocnemius, tibialis anterior, vastus medialis, vastus laterlis, biceps femoris, semitendinosus, adductor longus and tensor fascia muscles were recorded using ME 6000 system at a sampling frequency of 2000 HZ while performing each exercise. ANOVAs with repeated measures were employed for statistical analysis (p<0.05). The results indicated a greater myoelectric activity for vastus medialis and vastus lateralis muscles during performing hack squat and the squat exercises in comparison to the leg press exercise at different loads. The hack squat machine takes the pressure off the back and hips so can be used as a safe exercise for strengthen the quadriceps muscle group. Therefore, hack squat exercise could be recommended as a suitable exercise for both squat and leg press exercises among individuals with low back pain and sport injuries.
Article
[Purpose] A leg press generally included in a weight training program to develop the quadriceps. However little is known about the mechanism of the load in lower extremity by the different knee alignment. The purpose of this study is to compare the muscle activity in the different knee alignment during leg press exercise. [Methods] Four normal knee and Five genu varum performed the leg press using three stance of narrow, medium and wide stance with the load of 75%/1 RM. Surface EMG date were collected (1000 Hz) from vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), adductor longus (AL), biceps femoris (BF), tibialis anterior (TA), gastrocnemius (GAS), soleus (SOL). Integrated EMG (iEMG) values were calculated for each muscle during each rep. A video camera recorded the performing form during leg press from the frontal plane. [Results and Discussion] As the leg press was to strengthen of the thigh muscle. VM, VL and RF of both groups worked strongly. However SOL of genu varum worked as strong as the level of activity of the thigh, iEMG of the SOL showed low value significantly by using wide stance. When the genu varum group performed maximal knee flexion using the narrow, their ankle was valgus on the video screen. This result may become cause of SOL higher activity during leg press. From this we can derive the argument that it will be necessary to take that stance into consideration when athletes who are genu varum performs leg press.
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The purpose of this study was to compare hip and knee joint extension torque and the activity of eight muscles around the hip and knee joints during three squat exercises with different movements. Ten male athletes performed three different squats (Normal squat : NS, Knee push squat : KPS, Hip drive squat : HDS). KPS is the type of squat which emphasizes knee joint movement without moving the hip joint position back and forth. On the other hand, HDS is the type of squat which emphasizes hip joint movement, while keeping the knee joint position fixed. Kinematic and kinetic variables such as angle, angular velocity, net torque and power of the joints of the lower extremity were calculated during the descending and ascending phase of each squat. At the same time, surface electrodes were placed on eight muscles of the lower extremity, and %iEMG was also calculated during the same phases. During the descending phase, Elector spinae muscle activity and hip joint extension torque was significantly greater for HDS than KPS. Rectus femoris and Vastus lateralis muscle activity was significantly greater for KPS than HDS. In addition, KPS showed significantly greater knee joint extension torque than HDS and NS. At the ascending phase, Elector spinae, Glueus maximus and Biceps femoris muscle activity, and hip joint extension torque was significantly greater for HDS than KPS and NS. Rectus femoris muscle activity and knee joint extension torque was significantly greater for KPS than HDS and NS. These results suggest that HDS is effective for selectively training the hip extensor, and KPS is effective for training the Rectus femoris muscle.
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Injuries to the hamstring muscles can be devastating to the athlete because these injuries frequently heal slowly and have a tendency to recur. It is thought that many of the recurrent injuries to the hamstring musculotendinous unit are the result of inadequate rehabilitation following the initial injury. The severity of hamstring injuries is usually of first or second degree, but occasionally third-degree injuries (complete rupture of the musculotendinous unit) do occur. Most hamstring strain injuries occur while running or sprinting. Several aetiological factors have been proposed as being related to injury of the hamstring musculotendinous unit. They include: poor flexibility, inadequate muscle strength and/or endurance, dyssynergic muscle contraction during running, insufficient warm-up and stretching prior to exercise, awkward running style, and a return to activity before complete rehabilitation following injury. Treatment for hamstring injuries includes rest and immobilisation immediately following injury and then a gradually increasing programme of mobilisation, strengthening, and activity. Permission to return to athletic competition should be withheld until full rehabilitation has been achieved (complete return of muscle strength, endurance, and flexibility in addition to a return of co-ordination and athletic agility). Failure to achieve full rehabilitation will only predispose the athlete to recurrent injury. The best treatment for hamstring injuries is prevention, which should include training to maintain and/or improve strength, flexibility, endurance, co-ordination, and agility.
Article
This study investigated the muscular torques and joint forces during the parallel squat as performed by weightlifters. (JD)
Article
1. We have investigated the possibility that voluntary muscle lengthening contractions can be performed by selective recruitment of fast-twitch motor units, accompanied by derecruitment of slow-twitch motor units. 2. The behaviour of motor units in soleus, gastrocnemius lateralis and gastrocnemius medialis muscles was studied during (a) controlled isotonic plantar flexion against a constant load (shortening contraction, S), maintained plantar flexion, or dorsal flexion resisting the load and gradually yielding to it (lengthening contraction, L), (b) isometric increasing or decreasing plantar torque accomplished by graded contraction or relaxation of the triceps surae muscles, (c) isometric or isotonic ballistic contractions, and (d) periodic, quasi-sinusoidal isotonic contractions at different velocities. The above tasks were performed under visual control of foot position, without activation of antagonist muscles. The motor units discharging during foot rotation were grouped on the basis of the phase(s) during which they were active as S, S + L and L. The units were also characterized according to both the level of isometric ramp plantar torque at which they were first recruited and the amplitude of their action potential. 3. S units were never active during dorsal flexion; some of them were active during the sustained contraction between plantar and dorsal flexion. Most S + L units were active also during the maintenance phase and were slowly derecruited during lengthening; their behaviour during foot rotations was similar to that during isometric contractions or relaxations. L units were never active during either plantar or maintained flexion, but discharged during lengthening contraction in a given range of rotation velocities; the velocity of lengthening consistently influenced the firing frequency of these units. Such dependence on velocity was not observed in S + L units. 4. A correlation was found between the amplitude of the action potential and the threshold torque of recruitment among all the units. In addition, the amplitudes of both the action potential and the threshold torque were higher in the case of L units than in the case of S and S + L units. Most L units could be voluntarily recruited only in the case of ballistic isometric or isotonic contraction. 5. Occasionally, L units were directly activated by electrical stimulation of motor fibres and their conduction velocity was in the higher range for alpha-axons. In contrast, nerve stimulation could induce a reflex activation of S and S + L units.(ABSTRACT TRUNCATED AT 400 WORDS)
8 male subjects were tested to elucidate the organization of EMG activities in mono- and bi-articular thigh muscles when hip and knee extension are combined. 2 types of isometric movement, single and dual joint movements, were studied: 1) 20% of maximal voluntary contraction (MVC) in separate hip extension (HE20) and knee extension (KE20), 2) simultaneous HE20 and KE20, combined voluntarily (HE20.KE20). In HE20.KE20, the value of the integrated EMG (IEMG) from the muscles tested was normalized as a percentage (%IEMG) of the IEMG of each muscle in HE20 for gluteus maximus (GM) and semimembranosus (SM), and KE20 for vastus medialis (VM) and rectus femoris (RF). The average %IEMG was 50.5 +/- 16.9% for GM, 42.1 +/- 6.1% for SM, 153.4 +/- 22.8% for VM and 66.6 +/- 18.7% for RF. These data suggest that the EMG activities of GM, SM and RF are inhibited and the EMG activity of VM is facilitated by combining hip extension with knee extension.
Article
The objective of this study was to quantify the coacti vation patterns of the knee flexor and extensor muscles as part of continued efforts to identify the role of the antagonist muscles in maintaining joint stability. The simultaneous EMG from the flexor and extensor muscles of the knee were recorded during maximal effort, slow isokinetic contractions (15 deg/sec) on the plane parallel to the ground to eliminate the effect of gravity. The processed EMG from the antagonist mus cle was normalized with respect to its EMG as agonist at maximal effort for each joint angle. The plots of normalized antagonist EMG versus joint angle for each muscle group were shown to relate inversely to their moment arm variations over the joint range of motion. Additional calculations demonstrated that the antago nist exerts nearly constant opposing torque throughout joint range of motion. Comparison of data recorded from normal healthy subjects with that of high perform ance athletes with hypertrophied quadriceps demon strated strong inhibitory effects on the hamstrings coac tivations. Athletes who routinely exercise their ham strings, however, had a coactivation response similar to that of normal subjects. We concluded that coactivation of the antagonist is necessary to aid the ligaments in maintaining joint stability, equalizing the articular surface pressure dis tribution, and regulating the joint's mechanical imped ance. The reduced coactivation pattern of the unexer cised antagonist to a hypertrophied muscle increases the risk of ligamentous damage, as well as demon strates the adaptive properties of the antagonist muscle in response to exercise. It was also concluded that reduced risk of knee injuries in high performance ath letes with muscular imbalance could result from com plementary resistive exercise of the antagonist muscle.
Article
Injuries to the hamstring muscles can be devastating to the athlete because these injuries frequently heal slowly and have a tendency to recur. It is thought that many of the recurrent injuries to the hamstring musculotendinous unit are the result of inadequate rehabilitation following the initial injury. The severity of hamstring injuries is usually of first or second degree, but occasionally third-degree injuries (complete rupture of the musculotendinous unit) do occur. Most hamstring strain injuries occur while running or sprinting. Several aetiological factors have been proposed as being related to injury of the hamstring musculotendinous unit. They include: poor flexibility, inadequate muscle strength and/or endurance, dyssynergic muscle contraction during running, insufficient warm-up and stretching prior to exercise, awkward running style, and a return to activity before complete rehabilitation following injury. Treatment for hamstring injuries includes rest and immobilisation immediately following injury and then a gradually increasing programme of mobilisation, strengthening, and activity. Permission to return to athletic competition should be withheld until full rehabilitation has been achieved (complete return of muscle strength, endurance, and flexibility in addition to a return of co-ordination and athletic agility). Failure to achieve full rehabilitation will only predispose the athlete to recurrent injury. The best treatment for hamstring injuries is prevention, which should include training to maintain and/or improve strength, flexibility, endurance, co-ordination, and agility.
Article
The possible cause of hamstring strains was investigated in football players and track athletes, The subjects were divided into those who did (experimental) and those who did not (control) sustain hamstring strains. Five members of the San Diego Chargers football team and 12 track athletes made up the experimental group while 50 athletes were used as controls. Three tests, cable-tension knee flexion, cable-tension knee extension, and the sit-and-reach were administered to each subject. Two strength relationships were found significant at the .05 level. These relationships were concerned with the strength between the hamstrings, and unequal flexion-extension strength ratio. (C)1970The American College of Sports Medicine
Article
This study reports the histochemical fiber type composition of the human hamstring muscles. Muscle specimens from necropsy specimens were obtained from seven locations in the hamstring, four locations in the quadriceps, and one location in the adductor magnus. The hamstring muscles are shown to have a relatively high proportion of Type II fibers. Type II fibers are more involved with exercise of higher intensity and force production and it is postulated that the hamstrings are capable of high intrinsic force production. The hamstrings are two-joint muscles and are, therefore, subject to increased stretch and force production extrinsically by motion at the hip and knee. It is proposed that high levels of tension in the hamstrings produced by intrinsic force production and extrinsic stretch may make them prone to injury in periods of intense muscular activity. This proposal is also relevant to other frequent athletic muscle injuries.
Article
To examine how reaction forces and muscle activity change when transferring from a wheelchair to three different heights, six male able-bodied college students were tested. Analysis indicated that transferring to a lower seat position generated a greater vertical reaction force and required more muscle effort from triceps and posterior deltoid muscles. Transferring to a higher seat position resulted in a shift of the friction force from the anterior-posterior to the medial-lateral direction, and more biceps muscle effort was needed to perform the up-rightward movement. Transferring to a seat at the same height required less muscle effort from the upper extremities.
Strength, the common variable in hamstring strain
  • C S Christensen
CHRISTENSEN, C.S. Strength, the common variable in hamstring strain. Athletic Trainer 7:36–40. 1972.
Hamstring injuries in sprinters
  • S Jonhagen
JONHAGEN, S., G. NEMETH, AND E. ERIKSON. Hamstring injuries in sprinters. Am. J. Sports Med. 2:262–266. 1994.
the common variable in hamstring strain
  • C S Christensen
  • Strength
CHRISTENSEN, C.S. Strength, the common variable in hamstring strain. Athletic Trainer 7:36–40. 1972
Strength training and spotting techniques
  • R W Earle
  • And W B Allerheiligen
BAECHLE, T.R., R.W. EARLE, AND W.B. ALLERHEILIGEN. Strength training and spotting techniques. In: Essentials of Strength Training and Conditioning. Baechle, T.R., ed. Champaign: Human Kinetics, 1994. pp. 369–374.
Philadelphia: Lea and Febeger
  • And R K Burke
RASCH, P.J., AND R.K. BURKE. Kinesiology and Applied Anatomy (6th ed.). Philadelphia: Lea and Febeger, 1978. pp. 68, 273–298.
Hamstring injuries: Aetiological factors, prevention, and treatment
AGRE, J.C. Hamstring injuries: Aetiological factors, prevention, and treatment. Sports Med. 2:21–33. 1985.