Creatine phosphate recovery kinetics in female dancers, runners and sedentary controls

Hillman, Angela MSc, University of New Mexico, Albuquerque, New Mexico, USA; Robergs, Robert PhD, University of New Mexico, Albuquerque, New Mexico, USA; Altobelli, Stephen PhD, New Mexico Resonance, Albuquerque, New Mexico, USA; Caprihan, Arvind PhD, New Mexico Resonance, Albuquerque, New Mexico, USA; Wilmerding, Virginia PhD, University of New Mexico, Albuquerque, New Mexico, USA; and Wood, Jeff MSc, University of New Mexico, Albuquerque, New Mexico, USA

The purpose of this study was to quantify the rate of recovery in creatine phosphate (CrP) from the lateral gastrocnemius muscle of female dancers (DS), distance runners (RS), and sedentary subjects (SS).  It was hypothesized that the rigorous training of dancers would induce endurance training adaptations similar to long distance running, and that dancers and runners would recover faster, which is a sign of high mitochondrial density, than sedentary females.  Twenty-four subjects (8 DS, 9 RS, 7 SS) completed ankle plantar flexion exercise against resistance inside the bore of a 1.9 Tesla super-conducting magnet.  ³¹P magnetic resonance signals were acquired after a 100 ?s pulse, characterized by 512 data points (128 ms) every 500 ms; each pulse was gated to the start of each contraction recovery period.  Data were acquired at rest, during exercise, and for between 15 and 25 min of recovery, depending on subject specific exercise times.  Creatine phosphate was computed as the area under a Lorentzian curve for every 30 s averaged acquisition.  Non-linear curve fitting then provided data for the mono-exponential rate constant, and half time constant (t_0.5).  Rate constant data for the three groups were 0.66±0.31, 0.40±0.16, and 1.19±0.50, for DS, RS, and SS, respectively.  ANOVA for the three means was significant at p<0.001, with SS significantly greater than DS and RS.  For the t_0.5, data for the three groups were 1.38±0.83, 1.88±1.89, and 0.76±0.55, for DS, RS, and SS, respectively (NS).  Data indicated that sedentary controls had faster CrP recovery than trained dancers and runners.  The data reveal that CrP recovery may not be a sensitive measure of differences in muscle mitochondrial density in healthy women, as prior application of this method has been on individuals with metabolic diseases or abnormalities.  Dancers had similar CrP recovery kinetics to distance runners.