Cyclists and triathletes do not differ in muscle volume, muscle recruitment or pedal force effectiveness

BACKGROUND: Non-specific adaptation from training can elicit similar muscle volume and muscle activation between cyclists and triathletes which differ in comparison to non-athletes. OBJECTIVE: To compare muscle volume, muscle activation and pedal forces of cyclists, triathletes and non-athletes. METHODS: Twelve cyclists, ten triathletes and twelve non-athletes performed an incremental test to determine their maximal power output(PO MAX ). Quadriceps and triceps surae volume were estimated from ultrasound images taken at rest, while pedal forces and muscle activation were recorded at PO MAX at 90 rpm. RESULTS: Quadriceps volume was larger in cyclists (∼22%, p< 0.04) and triathletes (∼40%, p< 0.01) compared to non-athletes. Higher activation of rectus femoris (∼55%, p=0.01) and tibialis anterior(∼88%, p=0.01) were observed for triathletes compared to non-athletes at the first quarter of the pedaling cycle. Triathletes also showed higher activation for tibialis anterior than cyclists (∼68%, p=0.03) at the first quarter. Non-athletes applied greater force on the pedal compared to triathletes at the first quarter (∼42%, p< 0.01). Pedal force effectiveness was higher for athletes (37–44%, p< 0.02) compared to non-athletes at the fourth quarter. CONCLUSIONS: Similar muscle volume and muscle activation between cyclists and triathletes may be related to a similar training volume supporting differences relative to non-athletes.