The Effects of Resistance Training on Sport-Specific Performance of Elite Athletes: A Systematic Review with Meta-Analysis.

This systematic review examines the influence of resistance training (RT) on the performance outcomes of elite athletes. Adhering to PRISMA guidelines, a comprehensive search across PubMed, Scopus, SPORTDiscus, and Web of Science databases was conducted, considering studies up to November 19, 2023. The inclusion criteria were elite athletes involved in high-level competitions. Studies were categorized by the competitive level among elite athletes, athlete's sex, performance outcomes, and a training modality with subgroup analyses based on these factors. Thirty-five studies involving 777 elite athletes were included. The results of the meta-analysis revealed a large and significant overall effect of RT on sport-specific performance (standardized mean difference, SMD = 1.16, 95% CI: 0.65, 1.66), with substantial heterogeneity (I2 = 84%). Subgroup analyses revealed differential effects based on the competitive level, the type of sport-specific outcomes, and sex. National elite athletes showed more pronounced (large SMD) benefits from RT compared to international elite athletes (small SMD). Global outcomes revealed a medium but non-significant (p > 0.05) SMD, while local outcomes showed a large SMD. Notably, female athletes exhibited a large SMD, though not reaching statistical significance (p > 0.05), probably due to limited study participants. No significant (p > 0.05) differences were found between heavy and light load RT. Resistance training is effective in improving sport-specific performance in elite athletes, with its effectiveness modulated by the competitive level, the type of the performance outcome, and athlete's sex. The findings underscore the need for personalized RT regimens and further research, particularly in female elite athletes, as well as advanced RT methods for international elite athletes.

Musculoskeletal Injury Prevalence, Pain Perception, and Physical Activity Level Among Brazilian Strength and Cross-Training Practitioners.

In this study, we sought to determine the prevalence of musculoskeletal injuries, perceived pain, and physical activity level among Brazilian practitioners of strength training (ST) and functional fitness (FF). Participants were 311 men and women who trained in 10 FF training centers and seven ST gyms. Each participant completed surveys of the prevalence of musculoskeletal injuries, their pain perception, and their physical activity level. A chi square test was used to analyze associations between groups and distributions of injuries. When any significant difference was observed, the difference score was analyzed through the adjusted residual values. Fisher's exact test was used to determined the associations between musculoskeletal injury prevalence and training modality (FF and ST) and between musculoskeletal injury prevalence and practice frequency (times/wk). To measure the magnitude of association between variables, the Phi coefficient was calculated for 2x2 associations and Cramer's V was used whenever the distributions were outside this standard. When the dependent variable presented a dichotomous characteristic, an Odds Ratio (OR) was calculated with a confidence interval of 95%. We found a higher musculoskeletal injury prevalence in the axial skeleton (n = 52; 83.88%) in FF practitioners and in the lower limbs of ST practitioners (n = 9; 52.96%). When the physical activity level cutoff point was set at 300 minutes per week, there was a significant relationship between physical activity and training modality (p = 0.005). There was also a significant association between pain perception and musculoskeletal injury (p < 0.001). Clinical follow-up was a protective factor to being injured (OR = 0.18; CI = 0.06-0.49), and, even after multivariate analysis this significant association was maintained (OR = 0.03; CI = 0.01 - 0.08). Thus, FF practitioners reported more musculoskeletal injuries than STs, and follow-up medical or physical therapy was a protective factor to these injuries. FF practitioners also had a higher level of weekly physical activity weekly than ST practitioners. Functional fitness practitioners may be at a higher risk of injuries than those who participate in traditional strength training.

Internal Validity in Resistance Training Research: A Systematic Review.

Ensuring internal validity is the key procedure when planning the study design. Numerous systematic reviews have demonstrated that considerations for internal validity do not receive adequate attention in the primary research in sport sciences. Therefore, the purpose of this study was to review methodological procedures in current literature where the effects of resistance training on strength, speed, and endurance performance in athletes were analyzed. A computer-based literature searches of SPORTDiscus, Scopus, Medline, and Web of Science was conducted. The internal validity of individual studies was assessed using the PEDro scale. Peer-reviewed studies were accepted only if they met all the following eligibility criteria: (a) healthy male and female athletes between the ages of 18-65 years; (b) training program based on resistance exercises; (c) training program lasted for at least 4 weeks or 12 training sessions, with at least two sessions per week; (d) the study reported maximum strength, speed, or endurance outcomes; and (e) systematic reviews, cohort studies, case-control studies, cross-sectional studies were excluded. Of the 6,516 articles identified, 133 studies were selected for rating by the PEDro scale. Sixty-eight percent of the included studies used random allocation to groups, but only one reported concealed allocation. Baseline data are presented in almost 69% of the studies. Thirty-eight percent of studies demonstrated adequate follow-up of participants. The plan to follow the intention-to-treat or stating that all participants received training intervention or control conditions as allocated were reported in only 1.5% of studies. The procedure of blinding of assessors was also satisfied in only 1.5% of the studies. The current study highlights the gaps in designing and reporting research in the field of strength and conditioning. Randomization, blinding of assessors, reporting of attrition, and intention-to-treat analysis should be more fully addressed to reduce threats to internal validity in primary research.

Effects of Manual Therapies and Resistance Exercise on Postexercise Hypotension in Women With Normal Blood Pressure.

ABSTRACT: Monteiro, ER, Pescatello, LS, Winchester, JB, Corrêa Neto, VG, Brown, AF, Budde, H, Marchetti, PH, Silva, JG, Vianna, JM, and Novaes, JdS. Effects of manual therapies and resistance exercise on postexercise hypotension in women with normal blood pressure. J Strength Cond Res 36(4): 948-954, 2022-The purpose of this investigation was to examine the acute effects of resistance exercise (RE) and different manual therapies (static stretching and manual massage [MM]) performed separately or combined on blood pressure (BP) responses during recovery in women with normal BP. Sixteen recreationally strength-trained women (age: 25.1 ± 2.9 years; height: 158.9 ± 4.1 cm; body mass: 59.5 ± 4.9 kg; body mass index: 23.5 ± 1.9 kg·m-2; baseline systolic BP median: 128 mm Hg; and baseline diastolic BP median: 78 mm Hg) were recruited. All subjects performed 6 experiments in a randomized order: (a) rest control (CON), (b) RE only (RE), (c) static-stretching exercise only (SS), (d) MM only, (e) RE immediately followed by SS (RE + SS), and (f) RE immediately followed by MM (RE + MM). RE consisted of 3 sets of bilateral bench press, back squat, front pull-down, and leg press exercises at 80% of 10RM. Static stretching and MM were applied unilaterally in 2 sets of 120 seconds to each of the quadriceps, hamstring, and calf regions. Systolic (SBP) and diastolic BP were measured before (rest) and every 10 minutes for 60 minutes following (Post 10-60) each intervention. There were significant intragroup differences for RE in Post-50 (p = 0.038; d = -2.24; ∆ = -4.0 mm Hg). Similarly, SBP intragroup differences were found for the SS protocol in Post-50 (p = 0.021; d = -2.67; ∆ = -5.0 mm Hg) and Post-60 (p = 0.008; d = -2.88; ∆ = -5.0 mm Hg). Still, SBP intragroup differences were found for the MM protocol in Post-50 (p = 0.011; d = -2.61; ∆ = -4.0 mm Hg) and Post-60 (p = 0.011; d = -2.74; ∆ = -4.0 mm Hg). Finally, a single SBP intragroup difference was found for the RE + SS protocol in Post-60 (p = 0.024; d = -3.12; ∆ = -5.0 mm Hg). Practitioners should be aware that SS and MM have the potential to influence BP responses in addition to RE or by themselves and therefore should be taken into consideration for persons who are hypertensive or hypotensive.

Myoeletric Activity of the Quadriceps During Leg Press Exercise Performed With Differing Techniques.

Machado, W, Paz, G, Mendes, L, Maia, M, Winchester, JB, Lima, V, Willardson, JM, and Miranda, H. Myoeletric activity of the quadriceps during leg press exercise performed with differing techniques. J Strength Cond Res 31(2): 422-429, 2017-The quadriceps muscle supplies the motive force for dynamic knee extension. During this action, the vastus medialis oblique (VMO) and vastus lateralis (VL) co-contract to stabilize the patella as it tracks within the patellofemoral groove. The purpose of this study was to analyze surface electromyographic (SEMG) responses for the VL, VMO, rectus femoris (RF), and biceps femoris (BF), as well as the VMO:VL ratio during an open-kinetic chain 45° angled leg press (LP45). The traditional LP45 technique was compared with 2 alternative LP45 exercise techniques that used a physioball and elastic band, respectively. Thirteen female college students performed 3 protocols in random order: TRAD-1 LP45 set performed using the traditional exercise technique, PBALL-1 LP45 set performed with a physioball held between the knee joints, and PEB-1 LP45 set performed with an elastic band proximal to the knee joints. Ten repetitions at 70% of a 10 repetition maximum load were performed in each protocol, and the SEMG data were recorded for the VMO, VL, RF, and BF muscles. Significant increases in VMO activity were noted during PBALL vs. PEB (p = 0.001) and TRAD (p = 0.002). Higher VMO activity was noted during TRAD vs. PEB (p = 0.001). Greater VL activity was noted during PBALL vs. TRAD (p = 0.0001) and PEB (p = 0.0001). The PBALL condition elicited a greater VMO:VL ratio during the concentric phase vs. the PEB (p = 0.001) and TRAD (p = 0.001) protocols. Greater RF activity was observed during PEB vs. TRAD (p = 0.001) and PBALL (p = 0.001). Therefore, practitioners should consider placing a physioball between the knees during the LP45 exercise as an alternative technique when greater overall quadriceps activity is desired for clinical rehabilitation or a muscle strengthening program.

The Relationship Between Aerobic and Anaerobic Performance in Recreational Runners.

Research has indicated that combined aerobic and anaerobic training (concurrent training) may improve aerobic performance greater than aerobic training alone. The purpose of this investigation was to establish any associations between aerobic and anaerobic performance. Eleven participants (n = 11, age = 34.1 ± 13 years, VO2max = 58.4 ± 7.8) volunteered for this study. Participants were asked for endurance training experience (4.7 ± 3.7 years) and resistance training experience (4.1 ± 4.6 years). To meet training status, participants were to have a VO2max in the 80th percentile as per ACSM guidelines. The Bruce treadmill test was used to measure aerobic performance. In order to measure anaerobic performance, several tests were completed utilizing a force platform. A Pearson Product R Correlation Coefficient was calculated to determine correlations between variables. The results show significant correlation between VO2max and RFD (r = 0.68). Further analyses utilizing Cohen's effect size indicated a strong association between VO2max and peak force, as well as running efficiency and peak power, relative peak power, and power endurance. These results indicate an existing possibility that anaerobic performance measures such as RFD may have a positive relationship with aerobic performance measures such as VO2max. Therefore, it may be beneficial to integrate specific training components which focus on improving RFD as a method of improving running performance.

Balance comparisons between female dancers and active nondancers.

PURPOSE: Female dancers have lower anterior cruciate ligament (ACL) injury rates compared with physically active women. Enhanced balance can decrease musculoskeletal injury risk. Dancers are proposed to have superior balance compared with physically active nondancers, and this may reduce their risk for ACL injury. However, whether female dancers actually have better balance than active nondancers is unclear. METHOD: Thirty-three women (15 dancers, 18 nondancers) performed the Balance Error Scoring System (BESS; error scores), the Star Excursion Balance Test (SEBT; percent leg length), and the Modified Bass Test of Dynamic Balance (BASS; maximum score = 100). RESULTS: Dancers had fewer errors on the BESS than did nondancers (p < .001, 12.0 +/- 6.9 vs. 25.3 +/- 9.1). Dancers also had greater SEBT reach distances in the medial (right, p = .03, 90.4 +/- 4.2% vs. 86.5 +/- 5.5%; left, p = .04, 90.7 +/- 4.5% vs. 86.7 +/- 5.9%) and posteromedial directions (right, p = .01, 92.6 +/- 5.6% vs. 87.0 +/- 6.4%; left, p = .01, 93.9 +/- 6.3% vs. 87.9 +/- 6.3%), but not in the anteromedial direction (right, p = .23, 84.5 +/- 4.4% vs. 86.2 +/- 3.5%; left, p = .51, 86.4 +/- 3.5% vs. 85.5 +/- 4.0%). BASS scores were similar between groups (p = .58, 90.6 +/- 5.5 vs. 91.7 +/- 56). CONCLUSIONS: The novel findings of the study are that dancers had greater balance than did nondancers in some but not all tests. Although dancing may improve balance as compared with not dancing, it is not better than physical activity in improving balance. Thus, balance comparisons between dancers and nondancers may not fully explain why female dancers exhibit low ACL injury rates compared with physically active women. Other factors (e.g., anticipated/unanticipated movement demands) should be examined to understand the ACL injury disparity between dancers and physically active women.

Chronic effect of static stretching on strength performance and basal serum IGF-1 levels.

Improving the process of how physical performance is enhanced is one of the main topics evaluated by physiologists. This process often involves athletes and nonathletic populations. The purpose of this study was to assess the chronic response to 10 weeks of static stretching exercises carried out before and during a strength training program for 8 exercises on an 8 repetition maximum (8RM) test performance, and basal serum insulinlike growth factor (IGF-1) levels. Thirty recreationally trained volunteers were randomly assigned to 1 of 3 training groups: (a) SBST (performed a warm-up with a static stretching protocol before each strength training session); (b) SDST (before each training set, a static stretching exercise was performed); and (c) OST (entire session was performed without any type of stretching exercise). Strength and IGF-1 levels were collected at the beginning (pretest) and end (posttest) of the entire experimental procedure. All the exercises showed a significant increase in muscle strength for the OST group. However, the results revealed a significant increase in the muscle strength for only a few exercises in the SBST (LP, LE) and SDST (LP) experimental conditions. Significant statistical differences were found between SBST and SDST for all the exercises in the OST experimental condition. Furthermore, the IGF-1 expression showed no significant differences in the intragroup analysis. However, the OST group showed higher values (p < 0.05) in the posttest when compared with those of the other groups (increased significantly only in the OST experimental condition). It has been concluded that, although all the groups showed an increase in muscular strength, the strength training performed without any type of stretching exercise, regardless of whether the stretching is performed before or during the lifting session, can more effectively increase muscle strength and basal serum IGF-1 levels. It was concluded that strength training, with or without the use of stretching exercises, increased muscular strength in the studied groups, and can induce an increase in IGF-1 levels.

Upper-body muscular endurance in female university-level modern dancers: a pilot study.

Physical demands vary among dance styles, and injury patterns differ accordingly. Modern dance tends to be high in upper-body demands, and university-level female modern dancers are suggested to be at high risk for upper-body injury. Low muscular endurance is a known injury risk factor. Whether modern dancers have different upper-body muscular endurance than non-dancers is unclear. Thus, the purpose of this study was to compare upper-body endurance in female university-level modern dancers (n = 17) and physically active non-dancers (n = 15), using the modified push-up test. Pearson-correlations examined relationships between anthropometrics and push-ups. Multiple regression analyses were used to determine whether anthropometrics and physical activity could predict push-up scores. One-way ANOVAs compared upper-body endurance (number of push-ups) and physical activity between groups (p < 0.05). Except for height (r = -.37), no variables were related to push-ups. Neither anthropometrics nor physical activity were able to predict push-up scores (p = 0.25). Despite dancers being more active/day (3.6 ± 1.9 vs. 0.9 ± 0.4 hrs/day, p < 0.001), more times per week (5.4 ± 1.2 vs. 4.0 ± 1.8, p = 0.02), and having greater overall physical activity volumes (20.4 ± 11.4 vs. 3.3 ± 2.5 hrs/week, p < 0.001) than non-dancers, both groups had similar upper-body endurance (22.2 ± 8.6 vs. 19.9 ± 8.2, p = 0.44). A probable explanation for this similarity exists in the lack of physical activity beyond dance itself performed by the dancers; our preliminary work suggests that modern dance alone may not produce upper-body muscle endurance gains. Hence, it is suggested that modern dancers should engage in strength and conditioning training programs to enhance upper-body endurance.

A 10-week stretching program increases strength in the contralateral muscle.

It was questioned whether a unilateral stretching program would induce a crosstraining effect in the contralateral muscle. To test this, 13 untrained individuals participated in a 10-week stretching program while 12 other untrained individuals served as a control group. For the experimental group, the right calf muscle was stretched 4 times for 30 seconds, with a 30-second rest between stretches, 3 d·wk(-1) for 10 weeks. Strength, determined via 1 repetition maximum (1RM) unilateral standing toe raise, and range of motion (ROM) were measured pre-post. In the treatment group, the stretched calf muscle had a significant (p < 0.05) 8% increase in ROM, whereas the nonstretched calf muscle had a significant 1% decrease in ROM. The 1 RM of the stretched calf muscle significantly increased 29%, whereas the 1RM of the nonstretched calf muscle significantly increased 11%. In the control group, neither 1RM nor ROM changed for either leg. The results indicate that 10 weeks of stretching only the right calf will significantly increase the strength of both calves. Hence, chronic stretching can also induce a crosstraining effect for strength but not for the ROM. This study also validates earlier findings suggesting that stretching can elicit strength gains in untrained individuals.

Effects of unilateral and bilateral plyometric training on power and jumping ability in women.

Makaruk, H, Winchester, JB, Sadowski, J, Czaplicki, A, and Sacewicz, T. Effects of unilateral and bilateral plyometric training on power and jumping ability in women. J Strength Cond Res 25(12): 3311-3318, 2011-The purpose of this study was to examine the effects of unilateral and bilateral plyometric exercise on peak power and jumping performance during different stages of a 12-week training and detraining in women. Forty-nine untrained but physically active female college students were randomly assigned to 1 of 3 groups: unilateral plyometric group (n = 16), bilateral plyometric group (BLE; n = 18), and a control group (n = 15). Peak power and jumping ability were assessed by means of the alternate leg tests (10-second Wingate test and 5 alternate leg bounds), bilateral leg test (countermovement jump [CMJ]) and unilateral leg test (unilateral CMJ). Performance indicators were measured pretraining, midtraining, posttraining, and detraining. Differences between dependent variables were assessed with a 3 × 4 (group × time) repeated analysis of variance with Tukey's post hoc test applied where appropriate. Effect size was calculated to determine the magnitude of significant differences between the researched parameters. Only the unilateral plyometric training produced significant (p < 0.05) improvement in all tests from pretraining to midtraining, but there was no significant (p < 0.05) increase in performance indicators from midtraining to posttraining. The BLE group significantly (p < 0.05) improved in all tests from pretraining to posttraining and did not significantly (p > 0.05) decrease power and jumping ability in all tests during detraining. These results suggest that unilateral plyometric exercises produce power and jumping performance during a shorter period when compared to bilateral plyometric exercises but achieved performance gains last longer after bilateral plyometric training. Practitioners should consider the inclusion of both unilateral and bilateral modes of plyometric exercise to elicit rapid improvements and guard against detraining.

Endurance and resistance training lowers C-reactive protein in young, healthy females.

The purpose of this study was to determine whether endurance (E) or endurance + resistance (ER) training affects C-reactive protein (CRP) and if these changes are related to alterations in fitness and (or) body composition in young females. Thirty-eight females (aged 18-24 years) were assigned to 1 of 3 groups: (1) E, (2) ER or (3) active control (AC). The E and ER groups completed 15 weeks of marathon training. The ER group performed additional resistance training and the AC group maintained their usual exercise routine. Primary outcomes were measured pre- and post-training and included anthropometric indices, dual-energy x-ray absorptiometry, plasma CRP, time to complete 1.5 miles (in minutes), and upper and lower body strength tests (i.e., 8 repetition max on bench and leg press (ER group only)). There were no differences in any variable among the groups at baseline. After training, the E group decreased time to complete 1.5 miles (p < 0.05). The AC group decreased percent and absolute body fat while the E group decreased percent body fat, absolute body fat, and android and gynoid body fat (p < 0.05). The ER group significantly improved strength (p < 0.001) and reduced plasma CRP from 2.0 ± 1.1 to 0.8 ± 0.3 mg·L(-1) (p = 0.03). No significant associations were observed between CRP and measures of body composition or aerobic capacity. Combined endurance and resistance training may be an effective modality for reducing plasma CRP in young adult females independent of changes in aerobic capacity or body composition.

Relationship between isometric and dynamic strength in recreationally trained men.

The purpose of this investigation was to examine the relationships between measures of maximal isometric force (peak force [PF]), rate of force development (RFD), vertical jump performance (VJ) and 1-repetition maximum (1RM) strength in recreationally trained men. The subjects in this study were 26 men ([mean +/- SD]: age 22 +/- 1 years; height 175 +/- 7 cm; mass 90 +/- 10 kg). They were tested for PF using the isometric midthigh pull exercise. The 1RM for the squat and bench press exercise were determined as a measure of dynamic strength. Explosive strength was measured as RFD from the isometric force-time curve. Correlations between the variables were calculated using Pearson product moment correlation coefficient. There was a nearly perfect correlation between measures of PF and 1RM squat (r = 0.97, p < 0.05) and 1RM bench press (r = 0.99, p < 0.05). The correlations were very strong between VJ and PF (r = 0.72, p < 0.05) and 1RM bench press (r = 0.70, p < 0.05). There were also strong correlations between VJ and 1RM squat (r = 0.69, p < 0.05). There were no significant correlations with RFD. The results showed that isometric maximum strength determined during the isometric midthigh pull test correlated well with 1RM and VJ testing. However, RFD measured during the same test did not appear to correlate as well with other measures. The isometric midthigh pull provides an efficient method for assessing strength in recreationally trained individuals. Practitioners wishing to obtain performance data related to maximum strength may wish to consider isometric testing as a less time intensive method of testing.

Early-phase resistance training strength gains in novice lifters are enhanced by doing static stretching.

This study investigated differences in lower-body strength improvements when using standard progressive resistance training (WT) vs. the same progressive resistance training combined with static stretching exercises (WT + ST). Thirty-two college students (16 women and 16 men) were pair matched according to sex and knee extension 1 repetition maximum (1RM). One person from each pair was randomly assigned to WT and the other to WT + ST. WT did 3 sets of 6 repetitions of knee extension, knee flexion, and leg press 3 days per week for 8 weeks with weekly increases in the weight lifted. The WT + ST group performed the same lifting program as the WT group along with static stretching exercises designed to stretch the hip, thigh, and calf muscle groups. Stretching exercise sessions were done twice a week for 30 minutes during the 8-week period. WT significantly (p < 0.05) improved their knee flexion, knee extension, and leg press 1RM by 12, 14, and 9%, respectively. WT + ST, on the other hand, significantly (p < 0.05) improved their knee flexion, knee extension, and leg press 1RM by 16, 27, and 31, respectively. In addition, the WT + ST group had significantly greater knee extension and leg press gains (p < 0.05) than the WT group. Based on results of this study, it is recommended that to maximize strength gains in the early phase of training, novice lifters should include static stretching exercises to their resistance training programs.

A single 30-s stretch is sufficient to inhibit maximal voluntary strength.

While it has been well established that an acute stretching program can inhibit maximal muscle performance, the amount of stretching needed to produce the deleterious response is unknown. Therefore this study examined the dose-response relationship between acute stretching and strength inhibition. Eighteen college students performed a one repetition maximum (1-RM) test of knee-flexion following 0, 1, 2, 3, 4, 5, or 6 30-s bouts of hamstring stretching held at the limit of toleration. All seven dose variations were done by each subject, with each variation done on a separate day. One week separated each test, and the order of the stretch variations was balanced across the seven testing days. Stretching significantly (p < .05) reduced 1-RM after one 30-s stretch (5.4%), and continued to decrease 1-RM up to and including six 30-s stretches (12.4%). A single 30-s stretch, if held at the limit of toleration, is sufficient to cause an inhibition in a person's 1-RM. Additional bouts of stretching will further decrease the 1-RM, suggesting that multiple mechanisms may be involved in stretch-induced strength inhibition.

Changes in bar path kinematics and kinetics through use of summary feedback in power snatch training.

This study investigated kinematic and kinetic variable changes in the power snatch (PS) after 4 weeks of training and the use of summary feedback. Twenty-four collegiate football players participated as subjects in this study. The subjects were pretested for their 1-repetition maximum (1RM) and were separated into feedback (FG; n = 12) and control (CG; n = 12) groups. The FG was provided with augmented feedback (AF) during power snatch training sessions, which took place 3 times per week for 4 weeks. The AF is defined as information that is received in addition to what is naturally available. Variables measured include peak force (PF), peak power (PP), and several kinematic variables at 50, 70, and 90% of the subjects' pre-1RM. The PF was improved at 50% 1RM from 567 +/- 202 to 769 +/- 230 N, at 70% from 725 +/- 186 to 890 +/- 199 N, and at 90% from 822 +/- 197 to 1008 +/- 201 N in the FG (p

Eight weeks of ballistic exercise improves power independently of changes in strength and muscle fiber type expression.

This study investigated the effects of ballistic resistance training and strength training on muscle fiber composition, peak force (PF), maximal strength, and peak power (PP). Fourteen males (age = 21.3 +/- 2.9, body mass = 77.8 +/- 10.1 kg) with 3 months of resistance training experience completed the study. Subjects were tested pre and post for their squat one-repetition maximum (1RM) and PP in the jump squat (JS). Peak force and rate of force development (RFD) were tested during an isometric midthigh pull. Muscle biopsies were obtained from the vastus lateralis for analysis of muscle fiber type expression. Subjects were matched for strength and then randomly selected into either training (T) or control (C) groups. Group T performed 8 weeks of JS training using a periodized program with loading between 26 and 48% of 1RM, 3 days per week. Group T showed significant improvement in PP from 4088.9 +/- 520.6 to 5737.6 +/- 651.8 W. Rate of force development improved significantly in group T from 12687.5 +/- 4644.0 to 25343.8 +/- 12614.4 N x s(-1). PV improved significantly from 1.59 +/- 0.41 to 2.11 +/- 0.75 m x s(-1). No changes occurred in PF, 1RM, or muscle fiber type expression for group T. No changes occurred in any variables in group C. The results of this study indicate that using ballistic resistance exercise is an effective method for increasing PP and RFD independently of changes in maximum strength (1RM, PF), and those increases are a result of factors other than changes in muscle fiber type expression.

A proposed method for determining peak power in the jump squat exercise.

In recent years a great deal of research has been published using peak power (PP) in the jump squat (JS) exercise as a measure of athletic performance. However, no standardized method for the determination of PP exists at this time to accurately evaluate this variable. Our proposed method (PM) for determining PP (PPPM) in the JS uses the product of vertical ground reaction forces and velocity of the center of mass of both the subject and the external resistance of a loaded Olympic bar. Fifteen male subjects with a mean age of 27 +/- 3 years, weight of 78 +/- 17 kg, and height of 175 +/- 10 cm participated in this study. PP was measured in the JS at five different testing loads (30%, 35%, 40%, 45%, and 50% body weight) based on methods commonly discussed in the literature to compare PP results of previous methods to those obtained using the PM. Paired t-tests at different load levels were used for statistical analysis with an overall alpha = 0.05. The average PP among five testing loads, measured by the PM, was 3782 +/- 906 W. PP derived from the product of force and velocity of the bar alone was 72% lower than PPPM at 1057 +/- 243 W (P < 0.0001). The PP estimated by the product of bar velocity and vertical ground reaction forces of the bar plus the subject was 8% higher than PPPM at 4100 +/- 844 W (P = 0.0001). Our results indicate that using the methods traditionally reported in the literature may cause an overestimation of PP during athletic performance. Using the PM in future research will facilitate test validity and enable the generalization of results outside the scope of specific research projects.

Static stretching impairs sprint performance in collegiate track and field athletes.

Previous research has shown that static stretching (SS) can diminish the peak force output of stretch-shortening cycle actions while performing a dynamic warm-up (DW) protocol has been shown to enhance performance in similar activities. The purpose of this study was to establish whether the deleterious effects of SS would wash out the performance enhancements obtained from the DW. Eleven males and 11 females, who were athletes of a NCAA Division I track team, performed a DW followed with either a SS or rest (NS) condition. After warm-up was completed, three 40 m sprints were performed to investigate the effects of the SS condition on sprint performance when preceded by DW. Time(s) were obtained from timing gates placed at 0, 20, and 40 m respectively. Testing was conducted over 2 days with a 1 week washout period. Testing order was balanced to eliminate possible order effect. Time for the NS versus the SS group was significantly faster for the second 20 m with a time of 2.41 versus 2.38 seconds (P < or = .05), and for the entire 40 m with a time of 5.6 +/- 0.4 versus 5.7 +/- 0.4 seconds (P < or = .05). The results of this study suggest that performing a SS protocol following a DW will inhibit sprint performance in collegiate athletes.

The relationship between isometric and dynamic strength in college football players.

Previous research has demonstrated the importance of both dynamic and isometric maximal strength and rate of force development (RFD) in athletic populations. The purpose of this study was to examine the relationships between measures of isometric force (PF), RFD, jump performance and strength in collegiate football athletes. The subjects in this study were twenty-two men [(mean ± SD):age 18.4 ± 0.7 years; height 1.88 ± 0.07 m; mass 107.6 ± 22.9 kg] who were Division I college football players. They were tested for PF using the isometric mid thigh pull exercise. Explosive strength was measured as RFD from the isometric force-time curve. The one repetition maximum (1RM) for the squat, bench press and power clean exercises were determined as measures of dynamic strength. The two repetition maximum (2RM) for the split jerk was also determined. Vertical jump height and broad jump was measured to provide an indication of explosive muscular power. There were strong to very strong correlations between measures of PF and 1RM (r = 0. 61 - 0.72, p < 0.05). The correlations were very strong between the power clean 1RM and squat 1RM (r = 0.90, p < 0.05). There were very strong correlations between 2RM split jerk and clean 1RM (r = 0.71, p < 0.05), squat 1RM (r = 0.71, p < 0.05), bench 1RM (r = 0.70, p < 0.05) and PF (r = 0.72, p < 0.05). There were no significant correlations with RFD. The isometric mid thigh pull test does correlate well with 1RM testing in college football players. RFD does not appear to correlate as well with other measures. The isometric mid thigh pull provides an efficient method for assessing isometric strength in athletes. This measure also provides a strong indication of dynamic performance in this population. Key pointsIn Division I college football players the isometric mid thigh pull test correlates well with 1RM testing.Rate of Force Development does not appear to be as closely related to dynamic and isometric strength in college football players.The isometric mid thigh pull provides a quick and efficient method for assessing isometric strength in athletes.