For activities such as squash, badminton and fencing, the ability to quickly complete a lunge and return to the start or move off in another direction is critical for success. Determining which strength qualities are important predictors of lunge performance was the focus of this study. Thirty-one male athletes performed: (1) a unilateral maximal squat (one-repetition maximum, 1-RM) and unilateral jump squat (50% 1-RM) on an instrumented supine squat machine, and (2) a forward lunge while attached to a linear transducer. We performed stepwise multiple regression analysis with lunge performance as the dependent variable and various strength, flexibility and anthropometric measures as the independent variables. From the many strength and power measures calculated, time to peak force was the best single predictor of lunge performance, which accounted for 55% of the explained variance. The best three-variable model for predicting lunge performance accounted for 76-85% of the explained variance. The models differed, however, according to whether lunge performance was expressed relative to body mass (time to peak force, mean power and relative strength=76%) or taken as an absolute value (time to peak force, leg length and flexibility=85%). We conclude that one to two trials were reliable for strength diagnosis and that one strength measure cannot accurately explain functional performance because other factors, such as body mass, flexibility and leg length, have diverse effects on the statistical models.

Timing light systems are commonly used to measure sprint times of athletes. In this study, the reliability and effect of timing light height on sprint times was investigated. Two sets of timing lights set at hip and shoulder height, simultaneously timed subjects over 10 and 20 meters. The within-trial variation of both timing light heights were equally consistent; all coefficients of variation (CV) less than 1.2% with less variability associated with the longer (20 m) distances (CV < 0.85%). The typical error between the two timing light heights for both distances was small (< or = 1.3%). The mean difference between the two heights was significantly different (0.7 second, 95% CL = 0.05-0.10 second) at both the 10 and 20 m distances. Faster times were recorded at hip height as opposed to shoulder due to the legs breaking the beam before the upper body. It is suggested that standardized procedures are necessary for speed assessment using timing lights in order for comparisons to be made between athletic populations.

Eccentric strength training is thought to be important for improving functional performance. A form of training that may enhance the eccentric training stimulus is the attachment of a rubber bungy to the strength-training apparatus in such a way that the return velocity and, therefore, the force required to decelerate the load at the end of the eccentric phase are increased. To determine the effects of elastic bungy training, we performed two studies. In the first, we examined the electromyographic (EMG) and kinematic characteristics of three different squat techniques: traditional squat, non-bungy jump squat and bungy jump squat. In the second study, we examined whether jump squat training with and without the attachment of a rubber bungy to an isoinertial supine squat machine affects muscle function, multidirectional agility, lunge ability and single leg jump performance. The EMG activity of the vastus lateralis and gastrocnemius muscles was recorded. An instrumented isoinertial supine squat machine was used to measure maximal strength and various force, velocity and power measures in both studies. Participants were randomly assigned to one of three groups: a control group and two weight-trained groups, one of which performed bungy squat jumps and one of which performed non-bungy squat jumps. The two experimental groups performed 10 weeks of ballistic weight training. The kinematic and EMG characteristics of the bungy and non-bungy squat techniques differed significantly from those of the traditional squat on all the variables measured. The only difference between the bungy squat and non-bungy squat training was greater EMG activity during the later stages (70-100%) of the eccentric phase of the bungy squat condition. The 10 weeks of bungy squat and non-bungy squat jump weight training were found to be equally effective in producing improvements in a variety of concentric strength and power measures (10.6-19.8%). These improvements did not transfer to improved performance for the single leg jump and multidirectional agility. However, bungy weight training did lead to a significant improvement in lunge performance (21.5%) compared with the other groups.

The purpose of this study was to ascertain whether cluster training led to improved power training adaptations in the preseason preparation of elite level rugby union players. Eighteen highly trained athletes were divided into 2 training groups, a traditional training (TT, N = 9) group and a cluster training (CT, N = 9) group before undertaking 8 weeks of lower body resistance training. Force-velocity-power profiling in the jump squat movement was undertaken, and maximum strength was assessed in the back squat before and after the training intervention. Two-way analysis of variance and magnitude-based inferences were used to assess changes in maximum strength and force, velocity, and power values pretraining to posttraining. Both TT and CT groups significantly (p < 0.05) increased maximum strength posttraining. There was a possibly negative effect for the CT group on maximum strength when compared with that for the TT group (pretraining to posttraining change = 14.6 ± 18.0 and 18.3 ± 10.1%, respectively). There were no significant differences pretraining to posttraining for any jump squat force, velocity, or power measures. However, magnitude-based inferences showed that there was a likely positive effect of CT when compared with that of TT for peak power (pretraining to posttraining change = 7.5 ± 7.0 and 1.0 ± 6.2%, respectively) and peak velocity at 40 kg (pretraining to posttraining change = 4.7 ± 6.1 and 0.0 ± 5.0%, respectively) and for peak velocity at body weight (pretraining to posttraining change = 3.8 ± 3.4 and 0.5 ± 3.8%, respectively). Although both a traditional and cluster training loading pattern improved lower body maximum strength in a highly trained population, the traditional training structure resulted in greater maximum strength adaptation. There was some evidence to support the possible benefit of cluster type loading in training prescription for lower body power development.

CRONIN, J. B., P. J. McNAIR, and R. N. MARSHALL. The role of maximal strength and load on initial power production. Med. Sci. Sports Exerc., Vol. 32, No. 10, pp. 1763–1769, 2000. The influence of maximal strength, as measured by the maximal load lifted for one repetition (1RM), on power production in the initial 200 ms of the concentric phase for both rebound and nonrebound movements was investigated. We also investigated the effect of external load upon this relationship. Twenty-seven male subjects (21.9 ± 3.1 yr, 89.0 ± 12.5 kg) were separated by previously determined bench press 1RM into high (100.88 ± 7.24 kg) and low (72 ± 6.61 kg) RM groups. Concentric only bench presses and rebound bench presses were compared between and within groups to note the effect of RM across external loads of 40%, 60%, and 80% 1RM, on instantaneous, mean, and peak power output. The results of this study clearly indicated the enhancement of concentric motion by prior eccentric muscle action (336–1332% enhancement in the first 20 ms). Possessing a high RM augmented power production in the initial 200 ms of stretch-shorten cycle activity, across all the external resistances tested (P < 0.05). The temporal characteristics of this enhancement, however, differed across loads. That is, 80% 1RM loading showed a later time to peak enhancement (80 ms vs 20 ms). Interestingly, the influence of RM on concentric only motion in the initial 200 ms across the external resistances tested was found to be nonsignificant. The results suggest that the role of maximal strength during initial power production between concentric and stretch-shorten cycle activity differs, which has important implications for the training of athletes.