Effect of Lower-body vs Whole-body Resistance Exercise on Vastus Lateralis Deoxygenated Hemoglobin

Non-local fatigue occurs when one muscle group causes the fatigue of a different muscle group within a training session. This phenomenon may be explained by an increase in deoxygenated hemoglobin due to the competition of oxygenated blood between muscle groups. PURPOSE: Therefore the purpose of the study was to determine if adding upper body exercises to a lower body workout results in a significant difference in vastus lateralis deoxygenated hemoglobin values compared to lower body only. METHODS: One lower-body workout (LB) consisted of five sets of leg extension (quadriceps only exercise) at 90% of their maximum strength with 3-minutes between the beginning of each set. Another whole-body workout (WB) consisted of five sets of leg extension, and four sets of bench press and lat-pulldown was performed between bench press sets in an alternating manner, at 80% of maximal strength. For all exercises, sets 1-4 were performed for submaximal repetitions, and the fifth leg extension set was performed to exhaustion. A near infrared spectrometer device over the vastus lateralis was used to measure deoxygenated hemoglobin (HHb) at the beginning of every leg extension set. Analyses were performed in RStudio via R. Lme4 was used to run a mixed model to analyze the effects of set and condition on HHb. Emmeans was used to analyze post-hoc comparisons. Alpha was set at 0.05. RESULTS: There was a significant interaction between set and condition (p = 0.004). For set 1, there was no significant effect of workout condition (p = 0.48). For set 2, WB mean HHb (3.08 ± 2.70) was significantly higher than LB (0.85 ± 2.23) (p = 0.002, CI = 0.79–3.67). For set 3, WB (2.84 ± 2.24) was significantly higher than LB (1.29 ± 1.68) (p = 0.04, CI = 0.11–2.99). For set 4, WB (3.41 ± 1.71) was significantly higher than LB (0.30 ± 2.30) (p < 0.001, CI = 1.57–4.53). For set 5, WB (3.52 ± 1.91) was significantly higher than LB (0.36 ± 2.09) (p < 0.001, CI = 1.61–4.57). CONCLUSION: In conclusion adding lat pulldown and bench press did increase the concentration of deoxygenated hemoglobin in the vastus lateralis. This may be due to the competition of oxygenated blood between lower body and upper body muscles, which may at least partially explain the non-local fatigue effect observed in previous research.