Justin Nicoll1, Andrew C. Fry1, Loren Z. F. Chiu2, Brian K. Schilling3 & Lawrence W. Weiss3, FACSM

1University of Kansas, Lawrence, Kansas; 2University of Alberta, Edmonton, Alberta, Canada; 3University of Memphis, Memphis, Tennessee

Non-functional overreaching (NFOR) is detrimental to resistance exercise (RE) performance. Research concerning sensitive and sport specific methods that identify NFOR is sparse, and inconsistencies of results may be due to differences in testing modalities. PURPOSE: The purpose of this study was to compare muscle performance using different testing modalities (dynamic vs. isometric) after high power RE overreaching (OR). METHODS: As part of a larger dietary supplementation study, seventeen men (n=17; X±SD; age: 22.8±3.3yrs) were randomly assigned to a supplement (SUPP; n=8; body mass: 88.28±16.7kg; bodyfat: 11.7±6.4%), placebo (PL: n=3; bodymass: 86.66±25.7kg; bodyfat: 12.9±10.8%), or control (CON; n=6; body mass: 76.63±8.4kg, bodyfat: 11.3±6.8%) group. All groups participated in two weeks of normal training. After normal training, SUPP and PL performed OR for one week, while CON continued normal training. External mean power (MP), force (MF), and velocity (MV) were determined for the barbell squat exercise at 70% 1-RM load. Maximum isometric force, and rate of force development were determined using the isometric knee extension exercise on leg-extension machine interfaced with a force transducer. Performance data was collected at baseline (BL), after two weeks of normal training (Pre-OR), after OR phase (Post-OR), and after one week of recovery (POST). A 3x4 (group x time) repeated-measures ANOVA with Fisher LSD post-hoc was used to determine differences between groups and time. Significance was set at pRESULTS: There were no significant differences in knee extension variables (p>0.05). MF was higher in PL at Post-OR compared to BL and Pre-OR (2037 ± 626N vs. 1626±40N & 1581±92N; p-1 vs 78.7±11.3cm.s-1 & 75.3±6.7cm.s-1; p-1 vs 70.4±2.9cm.s-1 & 69.0±6.4cm.s-1; p0.05). CONCLUSION: Only dynamic RE (barbell squat) was sensitive to detect decreased performance compared to isometric RE (knee extension) in overreached subjects. Similarly, it appears power and velocity are more adversely affected by OR than measures of maximal force.

Funding provided by Nutricia.

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