Crank Rate Research Articles

Determination of peak oxygen uptake during upper body exercise

The purpose of this study was to determine (1) the repeatability of a currently recommended protocol for determination of VO2 peak during upper body exercise involving a crank rate of 60 rev min-1 (Hale et al. 1988), (2) whether employing a higher crank rate (70 rev min- 1) elicits higher VO2 peak values; (3) whether including an additional exercise stage 5 min after volitional exhaustion would elicit higher VO2 peak values. Twenty subjects (mean ± SD) age, height and body mass were 22·8 ± 1·8 years, 176 ± 5·0 cm and 77·5 ± 4·0 kg, respectively) visited the laboratory on three separate occassions. Subjects performed a different test to determine upper body VO2 peak on each visit. The tests were continuous and incremental in nature and were performed on a Monark cycle ergometer (Model 814E) adapted for arm exercise. Test 1 required subjects to exercise at a crank rate of 60 rev min-1 (60RPM-1). Test 2 was identical to test 1 (60RPM-2) but after 5 min recovery from the test subjects performed a further exercise stage (60RPM-F). Test 3 employed a crank rate of 70 rev min- 1 (70RPM). Five minutes after volitional exhaustion a further exercise stage was performed (70RPM-F). The levels of agreement for the 60 rev min- 1 protocol were ± 0.50 1 min- 1. All VO2 peak values achieved were within these limits. However, a higher VO2 peak was achieved by employing a crank rate of 70 rev min- 1 (p< 0.05). The VO2 peak achieved for 60RPM-F was similar to 60RPM whereas the VO2 peak for 70RPM-F tended to be less than that for 70RPM (p = 0.064). The results of this study suggest that the 60 rev min- 1 protocol can reliably determine VO2 peak, however it would appear to be more appropriate to employ a 70 rev min- 1 protocol as higher values were attained.

Maximal muscle power output in cycling: a modelling approach.

This study sought to find the optimal design parameters for a bicycle-rider system (crank length, pelvic inclination, seat height and rate of crank rotation) that maximise the power output from muscles of the human lower limb during cycling. The human lower limb was modelled as a planar system of five rigid bodies connected by four frictionless pin joints and driven by seven functional muscle groups. The muscles were assumed to behave according to an adapted form of Hill's (1938) equation, incorporating the muscle force-length relation. The force-length relation and the values of length that served as input into the relations of the various muscles were defined in the following two ways: (1) the force-length relation was parabolic, based on the experiment of Woittiez et al. (1984), and the length was defined as the whole muscle length; and (2) the force-length relation was expressed as a combination of lines, based on the cross-bridge theory, and the length was defined as muscle fibre length. In the second definition, the joint configurations at which four of the seven muscle groups reached optimal length (i.e. the length at which the muscle can exert maximal isometric force) were further given in two ways. The first way was consistent with a previous study from this laboratory (Yoshihuku and Herzog, 1990); the second way relied on unpublished experimental data. The dependence of the average power on the design parameters and definitions of the force-length relation and muscle length was examined. Maximal average power for one full crank rotation with a crank length of 0.17 m was found to be about 1300 W for definition 1 and 1000 W for definition 2. The average power was more sensitive to changes in design parameters in definition 2 than definition 1. The optimal rate of crank rotation with a crank length of 0.17 m was 18.4 rad s-1 (176 rev min-1) for definition 1 (this value is different from the result of the previous study due to revisions in input for two muscle groups), and 15.2 rad s-1 (145 rev min-1) and 14.6 rad s-1 (139 rev min-1) for definition 2.

Determination of maximal aerobic power during upper-body exercise.

The purpose of this investigation was to evaluate four protocols for their effectiveness in eliciting maximal aerobic power (peak VO2) during arm-crank exercise. Comparisons were made 1) between a continuous (CON) and an intermittent (INT) protocol (both employed a crank rate of 50 rpm) and 2) among the CON protocols employing crank rates of 30, 50, or 70 rpm. For the first group of experiments no significant (P greater than 0.05) differences were found between the CON and INT protocols for peak VO2, maximal pulmonary ventilation (VEmax), maximal heart rate (HRmax), or maximal blood lactate (LAmax) responses. For the second group of experiments, the CON-50 was compared with the CON-30 and CON-70 protocols. In comparison to the CON-50, significantly higher peak VO2 (+10%) and VEmax (+14%) responses were elicited by the CON-70 protocol, whereas significantly lower peak VO2 (-11%), VEmax (-23%), HRmax (-8%), and LAmax (-29%) responses were elicited by the CON-30 protocol. Of the arm-crank protocols examined the combination of a continuous design and a crank rate of 70 rpm provided the most effective protocol to elicit peak VO2 values.