Neuromuscular Adaptations to Same Versus Separate Muscle-Group Concurrent Aerobic and Strength Training in Recreationally Active Males and Females

Abstract

Combining aerobic and strength training may attenuate neuromuscular adaptations, particularly when both target the same muscle group. This study assessed whether separating the training modalities by muscle groups mitigates this interference. Ninety-six participants (56 males and 40 females) completed a 12-week intervention, divided into three groups: (1) LHLS (lower-body high-intensity interval (HIIT) and strength training), (2) LHUS (lower-body HIIT and upper-body strength training), and (3) LSUS (lower- and upper-body strength training). Maximal (1RM) and explosive strength were assessed using load-velocity profiling, with mean propulsive velocity (MPV) at 30%, 50%, 70%, and 90% of 1RM as a measure of explosive strength. Muscle cross-sectional area (CSA) of the M. vastus lateralis and M. pectoralis major was measured using panoramic ultrasound. Lower-body adaptations were compared between LHLS and LSUS, and upper-body adaptations were compared between LHUS and LSUS. MPV at 70% and 90% of 1RM for the squat (LHLS and LSUS) and bench press (LHUS and LSUS) showed improvements (p < 0.050), with no significant between-group differences. Squat 1RM improved in both LHLS and LSUS, and bench press 1RM increased in both LHUS and LSUS (all p < 0.001). M. vastus lateralis CSA increased in LHLS (p = 0.029) but not in LSUS, whereas M. pectoralis major CSA increased in both LHUS and LSUS (p < 0.001), with no between-group differences. No sex-based differences were observed. Concurrent aerobic and strength training does not impair explosive strength, maximal strength, or muscle hypertrophy, regardless of whether the same or separate muscle groups are targeted.

Keywords: interference effect; muscle hypertrophy; one‐repetition maximum; rapid force development.

FIGURE 1

Flowchart of the recruitment process. LHLS, lower‐body high‐intensity interval training (HIIT) and lower‐body strength; LHUS, lower‐body HIIT and upper‐body strength; LSUS, lower‐body and upper‐body strength.

FIGURE 2

(A) Absolute change in MPV in the squat for LHLS and LSUS over the 12‐week training period at 30% of the Week‐0 1RM clustered by sex. (B) Absolute change in MPV in the squat for LHLS and LSUS over the 12‐week training period at 50% of the Week‐0 1RM clustered by sex. LHLS, lower‐body high‐intensity interval training and lower‐body strength; LSUS, lower‐body and upper‐body strength; MPV, mean propulsive velocity.

FIGURE 3

(A) Absolute change in MPV in the squat for LHLS and LSUS over the 12‐week training period at 70% of the Week‐0 1RM clustered by sex. (B) Absolute change in MPV in the squat for LHLS and LSUS over the 12‐week training period at 90% of the Week‐0 1RM clustered by sex. *Indicates significant changes compared to pretraining intervention in LSUS. ^§Indicates significant changes compared to pretraining intervention in LHLS. LHLS, lower‐body high‐intensity interval training and lower‐body strength; LSUS, lower‐body and upper‐body strength; MPV, mean propulsive velocity.

FIGURE 4

(A) Absolute change in MPV in the bench press for LHUS and LSUS over the 12‐week training period at 30% of the Week‐0 1RM clustered by sex. (B) Absolute change in MPV in bench press for LHUS and LSUS over the 12‐week training period at 50% of the Week‐0 1RM clustered by sex. *Indicates significant changes compared to baseline in LSUS. ^§1Indicates significant changes compared to Week 4 in LHUS. LHUS, lower‐body high‐intensity interval training and upper‐body strength; LSUS, lower‐body and upper‐body strength; MPV, mean propulsive velocity.

FIGURE 5

(A) Absolute change in MPV in the bench press for LHUS and LSUS over the 12‐week training period at 70% of the Week‐0 1RM clustered by sex. (B) Absolute change in MPV in bench press for LHLS and LSUS over the 12‐week training period at 90% of the Week‐0 1RM clustered by sex. *Indicates significant changes compared to baseline in LSUS. ^§Indicates significant changes compared to baseline in LHUS. LHUS, lower‐body high‐intensity interval training and upper‐body strength; LSUS, lower‐body and upper‐body strength; MPV, mean propulsive velocity.

FIGURE 6

(A) 1RM in the squat for LHLS and LSUS over the 12‐week training period clustered by sex. (B) 1RM in the bench press for LHUS and LSUS over the 12‐week training period clustered by sex. *Indicates significant changes compared to baseline in LSUS. ^#Indicates significant changes compared to baseline in LHLS. ^§Indicates significant changes compared to baseline in LHUS. 1RM, one‐repetition maximum; HIIT, high‐intensity interval training; LHLS, lower‐body HIIT and lower‐body strength; LHUS, lower‐body HIIT and upper‐body strength; LSUS, lower‐body and upper‐body strength.

FIGURE 7

(A) M. vastus lateralis CSA in LHLS and LSUS over the 12‐week training period clustered by sex. (B) M. pectoralis major CSA in LHUS and LSUS over the 12‐week training period. *Indicates significant changes compared to baseline in LSUS. ^#Indicates significant changes compared to baseline in LHLS. ^§Indicates significant changes compared to baseline in LHUS. CSA, cross‐sectional area; HIIT, high‐intensity interval training; LHLS, lower‐body HIIT and lower‐body strength; LHUS, lower‐body HIIT and upper‐body strength; LSUS, lower‐body and upper‐body strength.