Effects Of Lower-body Versus Upper- And Lower-body Resistance Exercise On Lower-body Intramuscular Temperature

Abstract

PURPOSE: Intramuscular temperatures above 38.6° C are associated with impaired endurance. However, the effects of resistance exercise on intramuscular temperature has not been studied. Further, some studies have shown that exercise in one muscle group can impair performance in other muscles. Thus, the purpose of this study was to compare the effects of lower-body (LB) only and lower-body with upper-body (UB) resistance exercise on intramuscular temperature of the vastus lateralis. METHODS: Ten subjects (age=19.9±2.4 y; height=179.1±8.6 cm; mass=81.4±7.7 kg) participated in the study. Experimental visits consisted of either a LB or (UB) condition. During UB, participants completed three circuits of 90% one-repetition maximum (1RM) hip sled and 80% 1RM lat pull-down exercises to failure followed by a final 90% 1RM hip sled set to failure. During LB, participants completed four sets of hip sled to failure at 90% of 1RM. The beginning of each hip sled set was separated by 4-minutes. For all sets a thermocouple sampled vastus lateralis temperature. For all statistical analyses, alpha was set at .05. RESULTS: A 2 (condition) by 4 (set) by 2 [intra-set change (start versus end)] repeated measures ANOVA revealed a significant interaction between set and intra-set change on muscle temperature (p=.001; η2=.647); there were no other significant interactions. Collapsed across conditions, intra-set muscle temperature increases were progressively attenuated (highest p=.006) from a maximum of .5°±.2 in set 1 to .2°±.2 in set 4. There was no significant main effect of condition on muscle temperature (p=.257; η2=.140). Two one-sample t-tests showed that muscle temperature at the end of set 4 was significantly less than 38.6° in the LB (CI=35.6-37.2°; p<.001) and UB (CI=35.2-36.6°; p<.001) conditions. A 2 (condition) by 4 (set) repeated measures ANOVA yielded no significant main effect of condition on total number of completed hip sled repetitions (p=.494; η2=.053; LB CI=6.5-10.8 reps; UB CI=5.7-10.5). CONCLUSIONS: During resistance exercise, it is unlikely that muscle temperatures get high enough to enhance the rate of fatigue development. Furthermore, the addition of UB resistance exercise does not appear to significantly increase LB muscle temperature or affect performance under these conditions.