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.