Effects of high-intensity functional circuit training on motor function and sport motivation in healthy, inactive adults

Abstract

Purpose: A small share of the world's population meets current physical activity guidelines, which recommend regular engagement in endurance, strength, and neuromotor exercise. As lack of time represents a major cause of inactivity, multidimensional training methods with short durations may provide a promising alternative to classical, volume-oriented approaches focusing on one biomotor ability. This trial examined the effects of a high-intensity functional circuit training (HIFCT) on motor performance and exercise motivation in untrained adults.

Methods: Thirty-three inactive participants were randomly allocated to two groups exercising for six weeks. The intervention group (HIFCT, n = 20) 3×/week performed functional whole-body exercises in a circuit. Each 15-minute workout included repetitive 20s all-out bouts with 10s breaks. In the comparison group (moderate aerobic exercise, MAE, n = 13), the participants walked 3×/week for 50 minutes at moderate intensity. Measured motor outcomes were cycling endurance capacity (respiratory threshold, maximum workload), maximum strength (leg and chest press), postural control (force plate), and jump capacity (counter-movement jump, single leg hop for distance); exercise motivation was assessed using the self-concordance index.

Results: In comparison with MAE, HIFCT enhanced maximum leg strength (between-group difference of relative pre- to post-changes of 5.0%), shoulder strength (7.6%), and endurance workload (5.0%; P < 0.05), while increasing motivation to exercise (+5.5 points, P < 0.05). No between-group differences occurred for postural control and jump capacity (P > 0.05).

Conclusion: Despite considerably shorter training duration, HIFCT enhances motor function and motivation to exercise more effectively than MAE. Further research should investigate the long-term adherence to the program and its effectiveness in other settings.

Keywords: HIIT; circuit training; endurance; movement patterns; physical activity; strength trainin.