title: Muscle fibre type, efficiency, and mechanical optima affect freely chosen pedal rate during cycling.
abstract: This study investigated the variation in freely chosen pedal rate between subjects and its possible dependence on percentage myosin heavy chain I (%MHC I) in m. vastus lateralis, maximum leg strength and power, as well as efficiency. Additionally, the hypothesis was tested that a positive correlation exists between percentage MHC I and efficiency at pre-set pedal rates but not at freely chosen pedal rate. Twenty males performed cycling at low and high submaximal power output ( approximately 40 and 70% of the power output at which maximum oxygen uptake (VO(2max)) was attained at 80 r.p.m.) with freely chosen and pre-set pedal rates (61, 88, and 115 r.p.m.). Percentage MHC I as well as leg strength and power were determined. Freely chosen pedal rate varied considerably between subjects: 56-88 r.p.m. at low and 61-102 r.p.m. at high submaximal power output. This variation was only partly explained by percentage MHC I (21-97%) as well as by leg strength and power. Interestingly, %MHC I correlated significantly with the pedal rate at which maximum peak crank power occurred (r = -0.81). As hypothesized, %MHC I and efficiency were unrelated at freely chosen pedal rate, which was in contrast to a significant correlation found at pre-set pedal rates (r = 0.61 and r = 0.57 at low and high power output, respectively).
  
  
  CONCLUSIONS
  Subjects with high percentage MHC I chose high pedal rates close to the pedal rates at which maximum peak crank power occurred, while subjects with low percentage MHC I tended to choose lower pedal rates, favouring high efficiency. Nevertheless, the considerable variation in freely chosen pedal rate between subjects was neither fully accounted for by percentage MHC I nor by leg strength and power. Previously recognized relationships between percentage Type I ( approximately %MHC I) and efficiency as well as between pedal rate and efficiency were confirmed for pre-set pedal rates, but for freely chosen pedal rate, these variables were unrelated.
authors.affiliation: Institute of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, University of Southern Denmark.
authors.forename: E A
authors.initials: EA
authors.lastname: Hansen
authors.forename: J L
authors.initials: JL
authors.lastname: Andersen
authors.forename: J S
authors.initials: JS
authors.lastname: Nielsen
authors.forename: G
authors.initials: G
authors.lastname: Sjøgaard
mesh_terms: D000293:Adolescent; D000328:Adult; D001642:Bicycling; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D015444:Exercise / Q000502:physiology; D005080:Exercise Test / Q000379:methods*; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology
chemical_list: D018995:Myosin Heavy Chains