Change of muscle activation patterns in uphill cycling of varying slope

Abstract

In the present study, we quantitatively described and compared lower extremity neuromuscular patterns during level cycling (LC), 10 and 20% uphill cycling (UC). We hypothesized that both the timing and intensity of activity of selected lower extremity muscles will differ between steep (but not moderate slope) UC condition and LC. Twelve trained mountain bikers performed an experimental test with three different cycling conditions (level, 10% slope and 20% slope) with EMG monitoring of eight lower extremity muscles. Significant changes (p < 0.05) in muscle activation timing during 20% UC compared to LC (15° later onset and 39° earlier offset) were observed in m. rectus femoris (RF). Range of activity during 20% UC compared to LC was also significantly (p < 0.05) modified in m. vastus medialis, m. vastus lateralis (8° and 5° shorter) and m. biceps femoris (BF; 17° longer). Furthermore, a reduction of EMG activity level was observed for RF and m. tibialis anterior (TA) during 20% UC compared to LC (25 and 19%; p < 0.05), while the opposite effect was observed for m. gluteus maximus (GM; 12%; p < 0.05). Peak cross-correlation coefficients in all cycling conditions for all muscles were high (all coefficients ≥ 0.83). We have shown that altered body orientation during steep, but not moderate, slope UC significantly modified the timing and intensity of several lower extremity muscles, the most affected being those that cross the hip joint and TA. The observed modifications in neuromuscular patterns during 20% UC could have a significant effect on lower extremity joint kinetics and cycling efficiency.

From maturity to old age: tasks of daily life require a different muscle use in horses

“…The horses used in the present study were probably more different in their build, subcutaneous layer thickness and muscle volumes than the human cyclists investigated in other studies (Blake et al, 2012; Sarabon et al, 2012). Also, the muscles investigated in the present study are in constant use during the daily routine of the horses such as feeding and social grooming, and none of the horses were used athletically, therefore the degree of training and fine-tuning of the movements investigated was thought to be comparable between age groups.…”

Effects of Flat and Uphill Cycling on the Power-duration Relationship

“…It has been shown that field derived CP estimates may be considered as valid and reliable compared with laboratory esti-mates, whereas the reliability (and hence validity) of field derived W´ estimates is still debated [13,14]. However, previous research has shown that road gradient may partially affect biomechanical and physiological parameters like crank kinetics (e. g. crank inertial load, crank torque profile) [15][16][17], lower limb joint kinetics (e. g. joint moments, joint mechanical work) [18,19], lower limb neuromuscular activation (e. g. intensity and timing of EMG activity) [20][21][22] and gross efficiency [15,23] during cycling in a seated position. Furthermore, it has been shown that a certain metabolic rate (e. g. V ̇O2 and/or blood[lactate] at critical speed or CP) may be achieved by different interplays of muscle activity, muscle contraction and/ or muscle fibre type recruitment patterns, and external workrates [24,25].…”

Nose-down saddle tilt improves gross efficiency during seated uphill cycling

“…Regarding pedal forces, as the crank passes top dead center (0 • ), the reaction to rider-applied tangential pedal forces acts to push the rider backwards off the saddle and as the crank passes bottom dead center (180 • ) the pedal reaction force acts to pull the rider forward on the saddle. Leg muscle activation patterns during seated cycling on level, 5.7 • , and 11.3 • slopes suggest that riders may ingeniously adapt their pattern of pedal force application on steeper uphill slopes [5]. For example, on 5.7 • and 11.3 • slopes, subjects decreased their knee-extensor muscle (i.e., rectus femoris) activity by 13.9% and 25.3%, respectively.…”