Concurrent fatigue and potentiation in endurance athletes.

PURPOSE: Countermovement jump (CMJ) and maximum running speed over a distance of 20 m were evaluated for examination of the concurrent fatigue and postactivation potentiation (PAP) in endurance athletes after an incremental field running test. METHODS: Twenty-two endurance athletes performed two attempts of CMJ on a force plate and maximum running speed test before and following the Université de Montréal Track Test (UMTT). RESULTS: The results showed an improvement in CMJ height (3.6%) after UMTT that correlated with the increment in peak power (3.4%), with a concurrent peak force loss (-10.8%) that correlated with peak power enhancement. The athletes maintained their 20 m sprint performance after exhaustion. Cluster analysis reinforced the association between CMJ and peak power increments in responders with a reported correlation between peak power and sprint performance increments (r = .623; P = .041); nonresponders showed an impairment of peak force, vertical stiffness, and a higher vertical displacement of the center of mass during the countermovement that correlated with lactate concentration (r = -0.717; P = .02). CONCLUSIONS: It can be suggested that PAP could counteract the peak force loss after exhaustion, allowing the enhancement of CMJ performance and the maintenance of sprint ability in endurance athletes after the UMTT. From these results, the evaluation of CMJ after incremental running tests for the assessment of muscular adaptations in endurance athletes can be recommended.

Analysis of factors that influence the maximum number of repetitions in two upper-body resistance exercises: curl biceps and bench press.

The purpose of this study was to analyze the influence of exercise type, set configuration, and relative intensity load on relationship between 1 repetition maximum (1RM) and maximum number of repetitions (MNR). Thirteen male subjects, experienced in resistance training, were tested in bench press and biceps curl for 1RM, MNR at 90% of 1RM with cluster set configuration (rest of 30s between repetitions) and MNR at 70% of 1RM with traditional set configuration (no rest between repetitions). A lineal encoder was used for measuring displacement of load. Analysis of variance analysis revealed a significant effect of load (p<0.01) and a tendency in exercise factor (p=0.096), whereas the interaction effect was not significant. MNR at 70% of 1RM was lower for biceps curl (16.31+/-2.59 vs. 8.77+/-3 in bench press and biceps curl, respectively; p<0.05) and at 90% of 1RM (21.85+/-11.06 vs. 18.54+/-12.84 in bench press and biceps curl, respectively; p>0.05). Correlation between 1RM and MNR was significant for medium-intensity in biceps curl (r=-0.574; p<0.05) and between MNR and 1RM/body mass (r=-0.574; p<0.05). Neither 1RM nor 1RM/body mass correlated with velocity along set, so velocity seems to be similar at a same relative intensity for subjects with differences in maximum strength levels. From our results, we suggest the employment of MNR rather than % of 1RM for training monitoring. Furthermore, we suggest the introduction of cluster set configuration for upper-body assessment of MNR and for upper-body muscular endurance training at high-intensity loads, as it seems an efficient approach in looking for sessions with greater training volumes. This could be an interesting approach for such sports as wrestling or weightlifting.