Effects of weightlifting vs. kettlebell training on vertical jump, strength, and body composition

Effects of weightlifting vs. kettlebell training on vertical jump, strength, and body composition. J Strength Cond Res 26(5): 1199-1202, 2012-The present study compared the effects of 6 weeks of weightlifting plus traditional heavy resistance training exercises vs. kettlebell training on strength, power, and anthropometric measures. Thirty healthy men were randomly assigned to 1 of 2 groups: (a) weightlifting (n = 13; mean ± SD: age, 22.92 ± 1.98 years; body mass, 80.57 ± 12.99 kg; height, 174.56 ± 5.80 cm) or (b) kettlebell (n = 17; mean ± SD: age, 22.76 ± 1.86 years; body mass, 78.99 ± 10.68 kg; height, 176.79 ± 5.08 cm) and trained 2 times a week for 6 weeks. A linear periodization model was used for training; at weeks 1-3 volume was 3 × 6 (kettlebell swings or high pull), 4 × 4 (accelerated swings or power clean), and 4 × 6 (goblet squats or back squats), respectively, and the volume increased during weeks 4-6 to 4 × 6, 6 × 4, and 4 × 6, respectively. Participants were assessed for height (in centimeters), body mass (in kilograms), and body composition (skinfolds). Strength was assessed by the back squat 1 repetition maximum (1RM), whereas power was assessed by the vertical jump and power clean 1RM. The results of this study indicated that short-term weightlifting and kettlebell training were effective in increasing strength and power. However, the gain in strength using weightlifting movements was greater than that during kettlebell training. Neither method of training led to significant changes in any of the anthropometric measures. In conclusion, 6 weeks of weightlifting induced significantly greater improvements in strength compared with kettlebell training. No between-group differences existed for the vertical jump or body composition.     

The effect of short-term VertiMax vs. depth jump training on vertical jump performance

The ability to generate lower body explosive power is considered an important factor in many athletic activities. Thirty-one men and women, recreationally trained volunteers, were randomly assigned to 3 different groups (control, n = 10; VertiMax, n = 11; and depth jump, n = 10). A Vertec measuring device was used to test vertical jump height pre- and post-training. All subjects trained twice weekly for 6 weeks, performing approximately 140 jumps. The VertiMax group increased elastic resistance and decreased volume each week, while the depth jump group increased both box height and volume each week. The depth jump group significantly increased their vertical jump height (pre: 20.5 +/- 3.98; post: 22.65 +/- 4.09), while the VertiMax (pre: 22.18 +/- 4.31; post: 23.36 +/- 4.06) and control groups (pre: 15.65 +/- 4.51; post: 15.85 +/- 4.17) did not change. These findings suggest that, within the volume and intensity constraints of this study, depth jump training twice weekly for 6 weeks is more beneficial than VertiMax jump training for increasing vertical jump height. Strength professionals should focus on depth jump exercises in the short term over commercially available devices to improve vertical jump performance.     

Comparing short-term complex and compound training programs on vertical jump height and power output

The purpose of this study was to determine whether there were differences in vertical jump height and lower body power production gains between complex and compound training programs. A secondary purpose was to determine whether differences in gains were observed at a faster rate between complex and compound training programs. Thirty-one college-aged club volleyball players (11 men and 20 women) were assigned into either a complex training group or a compound training group based on gender and pre-training performance measures. Both groups trained twice per week for 4 weeks. Work was equated between the 2 groups. Complex training alternated between resistance and plyometric exercises on each training day; whereas, compound training consisted of resistance training on one day and plyometric training on the other. Our analyses showed significant improvements in vertical jump height in both training groups after only 3 weeks of training (P < 0.0001); vertical jump height increased by approximately 5% and 9% in the complex and compound training groups, respectively. However, neither group improved significantly better than the other, nor did either group experience faster gains in vertical leap or power output. The results of this study suggest that performing a minimum of 3 weeks of either complex or compound training is effective for improving vertical jump height and power output; thus, coaches should choose the program which best suits their training schedules.     

The relationship between vertical jump power estimates and weightlifting ability: a field-test approach

The purpose of this study was to assess the usefulness of the vertical jump and estimated vertical-jump power as a field test for weightlifting. Estimated PP output from the vertical jump was correlated with lifting ability among 64 USA national-level weightlifters (junior and senior men and women). Vertical jump was measured using the Kinematic Measurement System, consisting of a switch mat interfaced with a laptop computer. Vertical jumps were measured using a hands-on-hips method. A counter-movement vertical jump (CMJ) and a static vertical jump (SJ, 90 degrees knee angle) were measured. Two trials were given for each condition. Test-retest reliability for jump height was intra-class correlation (ICC) = 0.98 (CMJ) and ICC = 0.96 (SJ). Athletes warmed up on their own for 2-3 minutes, followed by 2 practice jumps at each condition. Peak power (PP) was estimated using the equations developed by Sayers et al. (24). The athletes' current lifting capabilities were assessed by a questionnaire, and USA national coaches checked the listed values. Differences between groups (i.e., men versus women, juniors versus resident lifters) were determined using t-tests (p < or = 0.05). Correlations were determined using Pearson's r. Results indicate that vertical jumping PP is strongly associated with weightlifting ability. Thus, these results indicate that PP derived from the vertical jump (CMJ or SJ) can be a valuable tool in assessing weightlifting performance.     

Short-term effects of selected exercise and load in contrast training on vertical jump performance

The present study examined the short-term effects of loaded half squats (HSs) and loaded jump squats (JSs) with low and moderate loads on the squat jump (SJ) and the countermovement jump (CMJ) performance using a contrast training approach. Ten men (mean +/- SD age, 23 +/- 1.8 years) performed the HS and JS exercises twice with loads of 30% of 1 repetition maximum (1RM) (HS30% and JS30%, respectively) and 60% of 1RM (HS60% and JS60%, respectively). On each occasion, 3 sets of 5 repetitions with 3 minutes of rest were performed as fast as possible. Vertical jump performance was measured before exercise, 1 minute after each set, and at the fifth and 10th minutes of recovery. The CMJ increased significantly after the first and second set (3.9%; p < 0.05) compared with preexercise values following the JS30% protocol and 3.3% after the second and third sets of the JS60% protocol. Following the HS60% protocol, CMJ increased after the first and the second sets (3.6%; p < 0.05) compared with preexercise values, whereas SQ increased only after the first set (4.9%; p < 0.05) in this condition. These data show that contrast loading with the use of low and moderate loads can cause a short-term increase in CMJ performance. The applied loads do not seem to present different short-term effects after loaded JSs. When the classic form of dynamic HS exercise is performed, however, at least a moderate load (60% of 1RM) needs to be applied.     

Squat jump training at maximal power loads vs. heavy loads: effect on sprint ability

Training at a load maximizing power output (Pmax) is an intuitively appealing strategy for enhancement of performance that has received little research attention. In this study we identified each subject's Pmax for an isoinertial resistance training exercise used for testing and training, and then we related the changes in strength to changes in sprint performance. The subjects were 18 well-trained rugby league players randomized to two equal-volume training groups for a 7-week period of squat jump training with heavy loads (80% 1RM) or with individually determined Pmax loads (20.0-43.5% 1RM). Performance measures were 1RM strength, maximal power at 55% of pretraining 1RM, and sprint times for 10 and 30 m. Percent changes were standardized to make magnitude-based inferences. Relationships between changes in these variables were expressed as correlations. Sprint times for 10 m showed improvements in the 80% 1RM group (-2.9 +/- 3.2%) and Pmax group (-1.3 +/- 2.2%), and there were similar improvements in 30-m sprint time (-1.9 +/- 2.8 and -1.2 +/- 2.0%, respectively). Differences in the improvements in sprint time between groups were unclear, but improvement in 1RM strength in the 80% 1RM group (15 +/- 9%) was possibly substantially greater than in the Pmax group (11 +/- 8%). Small-moderate negative correlations between change in 1RM and change in sprint time (r approximately -0.30) in the combined groups provided the only evidence of adaptive associations between strength and power outputs, and sprint performance. In conclusion, it seems that training at the load that maximizes individual peak power output for this exercise with a sample of professional team sport athletes was no more effective for improving sprint ability than training at heavy loads, and the changes in power output were not usefully related to changes in sprint ability.     

Effects of plyometric training and recovery on vertical jump performance and anaerobic power

We examined the effects of 2 plyometric training programs, equalized for training volume, followed by a 4-week recovery period of no plyometric training on anaerobic power and vertical jump performance. Physically active, college-aged men were randomly assigned to either a 4-week (n = 19, weight = 73.4 +/- 7.5 kg) or a 7-week (n = 19, weight = 80.1 +/- 12.5 kg) program. Vertical jump height, vertical jump power, and anaerobic power via the Margaria staircase test were measured pretraining (PRE), immediately posttraining (POST), and 4 weeks posttraining (POST-4). Vertical jump height decreased in the 4-week group PRE (67.8 +/- 7.9 cm) to POST (65.4 +/- 7.8 cm). Vertical jump height increased from PRE to POST-4 in 4-week (67.8 +/- 7.9 to 69.7 +/- 7.6 cm) and 7-week (64.6 +/- 6.2 to 67.2 +/- 7.6 cm) training programs. Vertical jump power decreased in the 4-week group from PRE (8,660.0 +/- 546.5 W) to POST (8,541.6 +/- 557.4 W) with no change in the 7-week group. Vertical jump power increased PRE to POST-4 in 4-week (8,660.0 +/- 546.5 W to 8,793.6 +/- 541.4 W) and 7-week (8,702.8 +/- 527.4 W to 8,931.5 +/- 537.6 W) training programs. Anaerobic power improved in the 7-week group from PRE (1,121.9 +/- 174.7 W) to POST (1,192.2 +/- 189.1 W) but not the 4-week group. Anaerobic power significantly improved PRE to POST-4 in both groups. There were no significant differences between the 2 training groups. Four-week and 7-week plyometric programs are equally effective for improving vertical jump height, vertical jump power, and anaerobic power when followed by a 4-week recovery period. However, a 4-week program may not be as effective as a 7-week program if the recovery period is not employed.     

Comparison of Olympic vs. traditional power lifting training programs in football players

Twenty members of an National Collegiate Athletic Association Division III collegiate football team were assigned to either an Olympic lifting (OL) group or power lifting (PL) group. Each group was matched by position and trained 4-days.wk(-1) for 15 weeks. Testing consisted of field tests to evaluate strength (1RM squat and bench press), 40-yard sprint, agility, vertical jump height (VJ), and vertical jump power (VJP). No significant pre- to posttraining differences were observed in 1RM bench press, 40-yard sprint, agility, VJ or in VJP in either group. Significant improvements were seen in 1RM squat in both the OL and PL groups. After log10-transformation, OL were observed to have a significantly greater improvement in Delta VJ than PL. Despite an 18% greater improvement in 1RM squat (p > 0.05), and a twofold greater improvement (p > 0.05) in 40-yard sprint time by OL, no further significant group differences were seen. Results suggest that OL can provide a significant advantage over PL in vertical jump performance changes.     

Training specificity of hurdle vs. countermovement jump training

The objective of this study was to compare bilateral and unilateral hurdle jumps with traditional countermovement jumps (CMJs). Thirteen athletes were tested during continuous forward bilateral and unilateral hurdle jumps and single CMJ. Countermovement jump height was used to establish the hurdle height. Subjects jumped forward over 4 hurdles with the force plate positioned after the second hurdle to measure vertical ground reaction force (VGRF), contact time (CT), and rate of force development (RFD). For bilateral jumps, hurdle height was established at maximal (100%) CMJ height and at 120, 140, and 160% of the CMJ height. The athletes were instructed to jump as fast as possible to mimic a training session drill. For unilateral jumps, hurdle height was set at 70, 80, and 90% of the CMJ height. Bilateral 160% jumps showed a significantly longer CT than bilateral 100, 120, and 140% jumps. The bilateral 100, 120, and 140% jumps had significantly shorter CT than the unilateral jumps and CMJ. The VGRF during bilateral jumps was higher than unilateral jumps and CMJ. Bilateral 160% jump RFD was significantly higher than CMJ and unilateral jumps but significantly lower than the other bilateral jumps. In conclusion, the characteristics of the bilateral jumps were substantially different from those of the CMJ and unilateral hurdle jumps. As bilateral hurdle jumps with a height between 100 and 140% of the CMJ provide similar CTs and VGRF as many reported sprint or jump actions, they may be considered a more training-specific power training drill than the CMJ.     

The effects of short-term unilateral and bilateral lower-body resistance training on measures of strength and power

The purpose of this study was to compare the effects of short-term unilateral resistance training (UL) and bilateral resistance training (BL) with free weights on several tests of unilateral and bilateral lower-body strength and power in men and women. Thirty-eight untrained men and women (mean body mass 78.3 +/- 21.47 kg; age 20.74 +/- 2.6 years) completed the study. The groups trained 2 days per week for 8 weeks with free weights and 2 days per week for 5 of the 8 weeks with plyometric drills. The resistance-training program consisted of a progression from 3 sets of 15 repetitions at 50% of the subject's predicted 1 repetition maximum (1RM) to 6 sets of 5 repetitions at 87% 1RM. Training volume and intensity were equal for each group. The free-weight squat was used to measure unilateral and bilateral strength. Power was measured by the Magaria-Kalamen stair-climb test and the unilateral and bilateral vertical jump test. Analysis of covariance was used to analyze differences between men and women and the interaction of group and gender. Pretest scores were used as the covariate. The UL group improved more than the BL group on the unilateral vertical jump height (p = 0.001) and relative power (p = 0.013). After adjusting for pretest differences, the improved scores on all tests, except for the unilateral squat, were similar between the men and the women. No significant interactions on all tests were found for the men or women comparison between training groups. These results indicate that UL and BL are equally effective for early phase improvement of unilateral and bilateral leg strength and power in untrained men and women.     

Enhancing jump performance after combined vs. maximal power, heavy-resistance, and plyometric training alone

Sáez Sáez de villarreal, E, Izquierdo, M, and Gonzalez-Badillo, JJ. Enhancing jump performance after combined vs. maximal power, heavy-resistance, and plyometric training alone. J Strength Cond Res 25(12): 3274-3281, 2011-The purpose of this study was to examine the effects of 5 different stimuli on jumping ability and power production after 7 weeks of training. Sixty-five (47 men and 18 women) physical education students were randomly assigned to 5 experimental groups that performed: combination of all training methods (A); heavy-resistance training using full-squat exercise (i.e., 56-85% of 1 RM for 3-6 repetitions) (B); power-oriented strength training using a parallel-squat exercise (i.e., 100-130% of load that maximizes power output for 2-6 repetitions) (C); power-oriented strength training using a loaded countermovement jumping (i.e., 70-100% of load that maximizes power output for 2-5 repetitions; countermovement jump [CMJ]) (D); and plyometric jumping (E). The CMJ (cm), loaded CMJ (cm), maximum rate of force development (RFDmax) during early concentric phase of loaded CMJ (N·s) and power output during early concentric phase of loaded CMJ (watts) were measured before and after 7 weeks of training. Significant improvements in CMJ (from 7.8 to 13.2%) were observed in all groups. Significantly greater increases in power output during loaded jumps were observed in A (10-13%) and D (8-12%) groups compared with in the other groups. Significant increases in RFDmax were observed in A (20-30%), C (18-26%), and D (20-26%) groups. The results of this study provide evidence to suggest that if training program is designed and implemented correctly, both traditional slow velocity training and faster power-oriented strength training alone, or in combination with plyometric training, would provide a positive training stimulus to enhance jumping performance.     

Short-term effects of strength and plyometric training on sprint and jump performance in professional soccer players

The purpose of this study was to compare the effects of combined strength and plyometric training with strength training alone on power-related measurements in professional soccer players. Subjects in the intervention team were randomly divided into 2 groups. Group ST (n = 6) performed heavy strength training twice a week for 7 weeks in addition to 6 to 8 soccer sessions a week. Group ST+P (n = 8) performed a plyometric training program in addition to the same training as the ST group. The control group (n = 7) performed 6 to 8 soccer sessions a week. Pretests and posttests were 1 repetition maximum (1RM) half squat, countermovement jump (CMJ), squat jump (SJ), 4-bounce test (4BT), peak power in half squat with 20 kg, 35 kg, and 50 kg (PP20, PP35, and PP50, respectively), sprint acceleration, peak sprint velocity, and total time on 40-m sprint. There were no significant differences between the ST+P group and ST group. Thus, the groups were pooled into 1 intervention group. The intervention group significantly improved in all measurements except CMJ, while the control group showed significant improvements only in PP20. There was a significant difference in relative improvement between the intervention group and control group in 1RM half squat, 4BT, and SJ. However, a significant difference between groups was not observed in PP20, PP35, sprint acceleration, peak sprinting velocity, and total time on 40-m sprint. The results suggest that there are no significant performance-enhancing effects of combining strength and plyometric training in professional soccer players concurrently performing 6 to 8 soccer sessions a week compared to strength training alone. However, heavy strength training leads to significant gains in strength and power-related measurements in professional soccer players.     

A deterministic model of the vertical jump: implications for training

Increasing vertical jump height is a critical component for performance enhancement in many sports. It takes on a number of different forms and conditions, including double and single legged jumps and stationary and run-up jumps. In an attempt to understand the factors that influence vertical jump performance, an extensive analysis was undertaken using the deterministic model. Once identified, practical training strategies enabling improvement in these factors were elucidated. Our analysis showed that a successful vertical jump performance was the result of a complex interplay of run-up speed, reactive strength, concentric action power of the take-off leg(s), hip flexors, shoulders, body position, body mass, and take-off time. Of special interest, our analysis showed that the concentric action power of the legs was the critical factor affecting stationary double leg vertical jumps, whereas reactive strength was the critical component for a single leg jump from a run-up.     

The effect of heavy- vs. light-load jump squats on the development of strength, power, and speed

The purpose of this investigation was to examine the effect of an 8-week training program with heavy- vs. light-load jump squats on various physical performance measures and electromyography (EMG). Twenty-six athletic men with varying levels of resistance training experience performed sessions of jump squats with either 30% (JS30, n = 9) or 80% (JS80, n = 10) of their one repetition maximum in the squat (1RM) or served as a control (C, n = 7). An agility test, 20-m sprint, and jump squats with 30% (30J), 55% (55J), and 80% (80J) of their 1RM were performed before and after training. Peak force, peak velocity (PV), peak power (PP), jump height, and average EMG (concentric phase) were calculated for the jumps. There were significant increases in PP and PV in the 30J, 55J, and 80J for the JS30 group (p 相似文献   

Comparison of land- and aquatic-based plyometric training on vertical jump performance

Plyometric training is a popular method by which athletes may increase power and explosiveness. However, plyometric training is considered a highly intense and potentially damaging activity particularly if practiced by the novice individual or if overdone. The purpose of this study was to compare vertical jump performance after land- and aquatic-based plyometric training. A convenience sample of 21 active, college-age (24 +/- 2.5 years) men were randomly assigned to 1 of 3 groups: group I, aquatic; group II, land; and group III, control. Training for the AQ and LN groups consisted of a 10-minute warm-up followed by 3 sets of 15 squat jumps, side hops, and knee-tuck jumps separated by 1-minute rests. The aquatic group performed the exercises in knee-level water adjusted to parallel the axis of the knee joint (+1 in.). The land group performed identical plyometric exercises on land. The control group engaged in no training. Participants trained twice a week for 6 weeks, and all training sessions were monitored. Pre- and post-test data were collected on maximum vertical jump height. A 2x3 analysis of variance with repeated measures was used to compare vertical jump height among the 3 groups. Results suggested that the aquatic- and land-based groups significantly (p < 0.05) outperformed the control group in the vertical jump. No significant difference was found in vertical jump performance between the aquatic- and land-based groups. It was concluded that aquatic training resulted in similar training effects as land-based training, with a possible reduction in stress due to the reduction of impact afforded by the buoyancy and resistance of the water upon landing.     

Short-term variability of blood pressure: effects of lower-body negative pressure and long-duration bed rest

Mild lower-body negative pressure (LBNP) has been utilized to selectively unload cardiopulmonary baroreceptors, but there is evidence that arterial baroreceptors can be transiently unloaded after the onset of mild LBNP. In this paper, a black box mathematical model for the prediction of diastolic blood pressure (DBP) variability from multiple inputs (systolic blood pressure, R-R interval duration, and central venous pressure) was applied to interpret the dynamics of blood pressure maintenance under the challenge of LBNP and in long-duration, head-down bed rest (HDBR). Hemodynamic recordings from seven participants in the WISE (Women's International Space Simulation for Exploration) Study collected during an experiment of incremental LBNP (-10 mmHg, -20 mmHg, -30 mmHg) were analyzed before and on day 50 of a 60-day-long HDBR campaign. Autoregressive spectral analysis focused on low-frequency (LF, ~0.1 Hz) oscillations of DBP, which are related to fluctuations in vascular resistance due to sympathetic and baroreflex regulation of vasomotor tone. The arterial baroreflex-related component explained 49 ± 13% of LF variability of DBP in spontaneous conditions, and 89 ± 9% (P < 0.05) on day 50 of HDBR, while the cardiopulmonary baroreflex component explained 17 ± 9% and 12 ± 4%, respectively. The arterial baroreflex-related variability was significantly increased in bed rest also for LBNP equal to -20 and -30 mmHg. The proposed technique provided a model interpretation of the proportional effect of arterial baroreflex vs. cardiopulmonary baroreflex-mediated components of blood pressure control and showed that arterial baroreflex was the main player in the mediation of DBP variability. Data during bed rest suggested that cardiopulmonary baroreflex-related effects are blunted and that blood pressure maintenance in the presence of an orthostatic stimulus relies mostly on arterial control.     

The acute effects of dynamic and ballistic stretching on vertical jump height, force, and power

Stretching before performance is a common practice among athletes in hopes of increasing performance and reducing the risk of injury. However, cumulative results indicate a negative impact of static stretching and proprioceptive neuromuscular facilitation (PNF) on performance; thus, there is a need for evaluating other stretching strategies for effective warm-up. The purpose of this study was to compare the differences between two sets of ballistic stretching and two sets of a dynamic stretching routine on vertical jump performance. Twenty healthy male and female college students between the ages of 22 and 34 (24.8 +/- 3 years) volunteered to participate in this study. All subjects completed three individual testing sessions on three nonconsecutive days. On each day, the subjects completed one of three treatments (no stretch, ballistic stretch, and dynamic stretch). Intraclass reliability was determined using the data obtained from each subject. A paired samples t-test revealed no significant difference in jump height, force, or power when comparing no stretch with ballistic stretch. A significant difference was found on jump power when comparing no stretch with dynamic stretch, but no significant difference was found for jump height or force. Statistics showed a very high reliability when measuring jump height, force, and power using the Kistler Quattro Jump force plate. It seems that neither dynamic stretching nor ballistic stretching will result in an increase in vertical jump height or force. However, dynamic stretching elicited gains in jump power poststretch.     

Kinetic analysis of complex training rest interval effect on vertical jump performance

Complex training has been recommended as a method of incorporating plyometrics with strength training. Some research suggests that plyometric performance is enhanced when performed 3-4 minutes after the strength training set, whereas other studies have failed to find any complex training advantage when plyometrics are performed immediately after the strength training portion of the complex. The purpose of this study was to determine if there is an ergogenic advantage associated with complex training and if there is an optimal time for performing plyometrics after the strength training set. Subjects were 21 NCAA Division I athletes who performed a countermovement vertical jump, a set of 5 repetitions maximum (5 RM) squats, and 5 trials of countermovement vertical jump at intervals of 10 seconds and 1, 2, 3, and 4 minutes after the squat. Jump height and peak ground reaction forces were acquired via a force platform. The pre-squat jump performance was compared with the post-squat jumps. Repeated measures ANOVA determined a difference (p 0.05) was found comparing subsequent jumps (0.72-0.76 m) to the pre-squat condition (0.74 m). When comparing high to low strength individuals, there was no effect on jump performance following the squat (p > 0.05). In conclusion, complex training does not appear to enhance jumping performance significantly and actually decreases it when the jump is performed immediately following the strength training set; however, a nonsignificant trend toward improvement seemed to be present. Therefore to optimize jump performance it appears that athletes should not perform jumps immediately following resistance training. It may be possible that beyond 4 minutes of recovery performance could be enhanced; however, that was not within the scope of the current study.     

Quantitative analysis of single- vs. multiple-set programs in resistance training

The purpose of this study was to examine the existing research on single-set vs. multiple-set resistance training programs. Using the meta-analytic approach, we included studies that met the following criteria in our analysis: (a) at least 6 subjects per group; (b) subject groups consisting of single-set vs. multiple-set resistance training programs; (c) pretest and posttest strength measures; (d) training programs of 6 weeks or more; (e) apparently "healthy" individuals free from orthopedic limitations; and (f) published studies in English-language journals only. Sixteen studies generated 103 effect sizes (ESs) based on a total of 621 subjects, ranging in age from 15-71 years. Across all designs, intervention strategies, and categories, the pretest to posttest ES in muscular strength was (chi = 1.4 +/- 1.4; 95% confidence interval, 0.41-3.8; p < 0.001). The results of 2 x 2 analysis of variance revealed simple main effects for age, training status (trained vs. untrained), and research design (p < 0.001). No significant main effects were found for sex, program duration, and set end point. Significant interactions were found for training status and program duration (6-16 weeks vs. 17-40 weeks) and number of sets performed (single vs. multiple). The data indicated that trained individuals performing multiple sets generated significantly greater increases in strength (p < 0.001). For programs with an extended duration, multiple sets were superior to single sets (p < 0.05). This quantitative review indicates that single-set programs for an initial short training period in untrained individuals result in similar strength gains as multiple-set programs. However, as progression occurs and higher gains are desired, multiple-set programs are more effective.     

The effects of drop vertical jump technique on landing and jumping kinetics and jump performance

The drop vertical jump is a popular plyometric exercise. Two distinct techniques are commonly used to initiate the drop vertical jump. With the ‘step-off’ technique, athletes step off a raised platform with their dominant limb, while their non-dominant limb remains on the platform. In contrast, with the ‘drop-off’ technique, athletes lean forward and drop off the platform, with both feet leaving the platform more simultaneously. The purpose of this study was to compare landing and jumping kinetics, inter-limb kinetic symmetry, and jump performance when individuals used the step-off and drop-off techniques, and to examine whether potential differences between these techniques are affected by platform height. Sixteen subjects completed drop vertical jumps with the drop-off and step-off techniques, from relatively low and high platform heights. Ground reactions forces were recorded for the dominant and non-dominant limbs during the land-and-jump phase of the drop vertical jump. Subjects demonstrated greater inter-limb asymmetry in peak impact forces when using the step-off technique, vs. the drop-off technique. This difference between the techniques was consistent across platform heights. The step-off technique appears to result in greater asymmetry in limb loading, which could contribute to the development of neuromuscular asymmetries between the limbs and/or asymmetric landing patterns.