Neuromuscular Adaptation to Resistance Training Involving Compound Exercises is Different between Caucasians and South Asians

Improvements in muscular strength (MS) during the initial stages of resistance training (RT) are attributed to adaptive alterations in nervous system function independent of muscular hypertrophy. Differential responses to short term RT have been identified between several racial groups however; differences in neuromuscular adaptation between Caucasian (CAUC) and South Asian (SOU) males are unknown. PURPOSE: To examine MS responses to 6 weeks RT in CAUC and SOU individuals. METHODS: Fifteen CAUC (25 ± 4 yrs) and thirteen SOU (25 ± 7 yrs) apparently healthy males participated in a whole body progressive RT protocol 3 x week-1 for 6 weeks. Training consisted of five core exercises: squats, military press, lateral pull downs, bench press and deadlifts split into 2 sessions (S-A, S-B) which were completed consecutively. Squats were performed in every exercise session. Upper body (UB) and lower body (LB) MS pre and post of RT was measured by 3-repetition maximum (3RM) of bench press and squat. Progression of RT was recorded in both groups Differences between groups, time points and their interaction were established by mixed methods repeated measures ANOVA. Statistical significance was set at p<0.05. All data are presented as mean difference (Δ) ± SD. RESULTS: Baseline UB and LB 3RM were similar between groups (UB p=0.72; LB p=0.45). Following RT, UB and LB 3RM significantly increased (p<0.001) in the CAUC group (UB: Δ 13.7 ± 1.6 Kg; LB: Δ 61.3 ± 3.8 Kg) and SOU group (UB: Δ 11.9 ± 1.8 Kg; LB: Δ 42.7 ± 4.0 Kg). CAUC LB 3RM improved greater than SOU following RT (p=0.002). The accumulated load lifted in S-A and S-B improved (p<0.001) in both groups with a time interaction between groups identified (S-A: CAUC Δ 112.9 ± 2.6 Kg; SOU Δ 106 ± 3.8 Kg, p=0.02; S-B: CAUC Δ 138 ± 6.1 Kg; SOU Δ 110.8 ± 6.5 Kg, p=0.03). Significant increases in progression were observed in all core exercises in both groups (all p<0.001). A time interaction between groups was identified in week 2 of squat progression (p=0.03) which strengthened as RT progressed. When squat exercises were excluded from analysis, no interactions in S-A or S-B between groups were observed (p>0.05 for both sessions). CONCLUSION: Although SOU respond similarly to CAUC to RT, the rate of progression to large coordinated movement differs between groups which highlight potential differences in neuromuscular adaptation.