Activity: Talks and presentations › Talks and presentations in private or public companies
The leading joint hypothesis (LJH) deals with control of human rhythmic movement, e.g. pedaling. According to Dounskaia (2005) the leading joint (e.g. hip joint in pedaling) "creates a dynamic foundation for motion of the entire limb. Acceleration/deceleration at the leading joint is produced by reciprocal muscle activity in the same way as during single-joint movements, i.e. largely disregarding motion at the other joints". LJH is developing and it is e.g. unknown if the hip flexor or extensor system primarily is controlling freely chosen cadence (FCC). Twelve weeks of heavy strength training reduced FCC by 10 rpm in healthy subjects (Hansen et al. 2007). Could the training somehow have affected the behavior, via changes in the neuromuscular-tendon system involved in hip joint movement? Since subjects trained both hip flexion and extension we cannot elucidate if in particular the flexion or extension caused the changed FCC. Here, we test if heavy squat strength training (HSST), particularly involving hip extension, affects FCC.
Healthy males (n=8, 24±5 years, 82±6 kg, 181±5 cm) did 12 wk of progressive HSST (180-60 deg. knee angle, free weights, 10RM-3RM, 3-5 sets/session, 3 sessions/wk, 85±9% adherence). Healthy males (n=7, 29±3 years, 83±4 kg, 186±7 cm) were controls. Vertical force in maximal isometric squat at 90 deg. knee angle performed on a force plate represented strength. Cadence was averaged over the last 2 min of a 5-min bout at 2 W/kg on a Lode Excalibur Sport.
Body mass was unchanged by intervention. Strength increase (14±7%) was larger (p<0.05) in the HSST group than among controls (-2±9%) and averaged 1257±326 N at baseline, across groups. Cadence was unchanged by intervention and averaged 73±12 rpm at baseline, across groups.
HSST did not affect FCC. This, combined with earlier findings, might point at the hip flexor system for control of FCC.
Dounskaia N. 2005. Exp Brain Res 166, 1-16
Hansen EA, Raastad T & Hallén J. 2007. Eur J Appl Physiol 101, 419-26