Heart rate and performance parameters in elite cyclists: a longitudinal study. :

In a comparison of traditional and theoretical exercise efficiency calculations male subjects were studied during steady-rate cycle ergometer exercises of "0," 200, 400, 600, and 800 kgm/min while pedaling at 40, 60, 80, and 100 rpm. Gross (no base-line correction), net (resting metabolism as base-line correction), work (unloading cycling as base-line correction), and delta (measurable work rate as base-line correction) efficiencies were computed. The result that gross (range 7.5-20.4%) and net (9.8-24.1%) efficiencies increased with increments in work rate was considered to be an artifact of calculation. A LINEAR OR SLIGHTLY EXPONENTIAL RELATIONSHIP BETWEEN CALORIC OUTPUT AND WORK RATE DICTATES EITHER CONSTANT OR DECREASING EFFICIENCY WITH INCREMENTS IN WORK. The delta efficiency (24.4-34.0%) definition produced this result. Due to the difficulty in obtaining 0 work equivalents, the work efficiency definition proved difficult to apply. All definitions yielded the result of decreasing efficiency with increments in speed. Since the theoretical-thermodynamic computation (assuming mitochondrial P/O = 3.0 and delta G = -11.0 kcal/mol for ATP) holds only for CHO, the traditional mode of computation (based upon VO2 and R) was judged to be superior since R less than 1.0. Assuming a constant phosphorylative-coupling efficiency of 60%, the mechanical contraction-coupling efficiency appears to vary between 41 and 57%.

This study was undertaken to determine which of four commonly used ventilatory or gas exchange indices provides the most accurate and reliable detection of the anaerobic threshold (AT). Sixteen subjects performed two cycle ergometer tests to volitional fatigue. After 4 min of unloaded cycling, the work rate was increased 20 W/min. Ventilatory and gas exchange measurements were made every 30 s throughout each test. During one of the two tests (randomly assigned), venous blood was also sampled every 30 s for subsequent determinations of blood lactate (HLa) concentration. Four ventilatory and gas exchange indices (VE, VCO2, R, VE/VO2) were used separately to detect the AT. The AT determined from systematic increases in HLa concentration was used as the criterion measure. AT values (means +/- SE) (VO2, l/min) using VE, VCO2, R, VE/VO2, and HLa were 1.79 +/- 0.11, 1.74 +/- 0.11, 1.58 +/- 0.06, 1.84 +/- 0.11, and 1.85 +/- 0.11 l/min, respectively. The highest correlation between a ventilatory or gas exchange AT and ATHLa (i.e., criterion measure) was found for VE/VO2 (r=0.93, P less than 0.001). The VE/VO2 also provided the highest test-retest correlation for detection of the AT (r = 0.93, P less than 0.001). Multiple correlational analyses did not significantly enhance detection of the AT. These results favor the use of VE/VO2 for noninvasive detection of the AT because it proved to be the most sensitive and reliable ventilatory or gas exchange index studied.

Fifteen male runners were tested on two occasions to determine the reliability of a continuous incremental level running treadmill protocol (C), with 3-min stages, for lactate threshold (LT) and fixed blood lactate concentration (FBLC) (2.0 mM, 2.5 mM, 4.0 mM) assessment. Test-retest (T-RT) reliability coefficients for velocity at LT, 2.0 mM, 2.5 mM, and 4.0 mM were r = 0.89, 0.91, 0.95, and 0.95, respectively (velocity ranged from 215.3 m/min at LT to 273.6 m/min at 4.0 mM). Mean differences in T-RT velocity values ranged from 0.7 m/min (at LT) to 6.0 m/min (at 2.5 mM; 252.3 m/min vs 258.3 m/min; NS) and the standard errors of measurement were less than +/- 10.0 m/min. Similar results were observed for VO2, with T-RT r values ranging from r = 0.82 (at LT) to r = 0.88 (at 2.0 mM) (VO2 ranged from 47.2 ml/kg.min-1 at LT to 60.9 ml/kg.min-1 at 4.0 mM; VO2 peak = 65.6 ml/kg.min-1). Mean differences in T-RT VO2 values were less than 1.4 ml/kg.min-1 (NS) and the standard errors of measurement were less than +/- 2.95 ml/kg.min-1. Interinvestigator and intrainvestigator reliability coefficients were high and ranged from r = 0.91 to r = 0.99. Validity of C was assessed in an additional 16 male runners who completed C and a criterion discontinuous (D) protocol (using a series of 10-min stages) for LT and FBLC assessment. Results indicated that C and D resulted in similar VO2 and velocity values at LT and FBLC.(ABSTRACT TRUNCATED AT 250 WORDS)