Effect of posture on high-intensity constant-load cycling performance in men and women

Abstract

The time sustained during a graded cycle exercise is approximately 10% longer in an upright compared with a supine posture. However, during constant-load cycling this effect is unknown. Therefore, we tested the postural effect on the performance of high-intensity constant-load cycling. Twenty-two active subjects (11 men, 11 women) performed two graded tests (one upright, one supine), and of those 22, 10 subjects (5 men, 5 women) performed three high-intensity constant-load tests (one upright, two supine). To test the postural effect on performance at the same absolute intensity, during the upright and one of the supine constant-load tests subjects cycled at 80% of the peak power output achieved during the upright graded test. To test the postural effect on performance at the same relative intensities, during the second supine test subjects cycled at 80% of the peak power output achieved during the supine graded test. Exercise time on the graded and absolute intensity constant-load tests for all subjects was greater (P<0.05) in the upright compared with supine posture (17.9+/-3.5 vs. 16.1+/-3.1 min for graded; 13.2+/-8.7 vs. 5.2+/-1.9 min for constant-load). This postural effect at the same absolute intensity was larger in men (19.4+/-8.5 upright vs. 6.6+/-1.6 supine, P<0.001) than women (7.1+/-2 upright vs. 3.9+/-1.4 supine, P>0.05) and it was correlated (P<0.05) with both the difference in VO2 between positions during the first minute of exercise (r=0.67) and the height of the subjects (r=0.72). In conclusion, there is a very large postural effect on performance during constant-load cycling exercise and this effect is significantly larger in men than women.

Intensity-dependent effect of body tilt angle on calf muscle fatigue in humans

“…The tilt-induced eVect of blood Xow on muscle fatigue appears to be mediated by O 2 and its delivery to exercising muscle (Hogan et al 1994), although there might also be a contribution from an O 2 -independent mechanism such as waste-product removal (Barclay 1986). A mechanistic role for O 2 is further supported by the evidence that upright tilting of the human body increases the responses of both muscle blood Xow and pulmonary VO 2 during the Wrst minute of knee extensor exercise (MacDonald et al 1998) and cycling (Egaña et al 2006;Koga et al 1999). …”

“…Raising active muscles above the level of the heart increases their fatigue; whereas lowering muscles to below the level of the heart decreases their fatigue. These eVects have been observed for muscles of the upper limb (Fitzpatrick et al 1996;Wright et al 1999) and lower limb (Egaña and Green 2005;Egaña et al 2006;Tachi et al 2004), as well as during voluntary (Egaña and Green 2005;Egaña et al 2006;Tachi et al 2004;Wright et al 1999) and involuntary (Fitzpatrick et al 1996) exercise. The underlying mechanism(s) probably involve muscle blood Xow and its inXuence on O 2 supply and consumption (see Discussion); but do not appear to be related to muscle strength (Egaña and Green 2005).…”

Effect of body tilt angle on fatigue and EMG activities in lower limbs during cycling

“…This effect is much larger for high-intensity (i.e. ~80% Peak Power, PP) constant-load exercise than for maximal graded exercise (~100 vs 15%) and it is independent of gender and/or aerobic capacity ( max ) (Egaña et al 2006; ). This postural effect on cycling performance is associated with a faster 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 ...…”

Wireless Body Area Network for Cycling Posture Monitoring

“…For this purpose, one node is placed in the upper leg and the other is placed on the lower leg. The knee angle between these two body segments is given by (4).…”

“…Moreover, the upright position makes the cycling exercise less costly during steady state. In [4], the authors conclude that the posture has a very large effect on the performance of active cyclists during constant-load exercises.…”