Improving the power output at the lactate threshold with a training programme of low-cadence cycling

Abstract

One of the major aims of training for competitive endurance events is to improve the oxidative capacity of the event-specific skeletal muscle fibres and in so doing improve the exercise intensity at the lactate threshold (T .T) for the particular discipline. The LT has been shown to correlate highly with performance in endurance events. To be stimulated to adapt, a muscle has to be recruited. Low intensity training preferentially recruits and causes adaptation in Type I fibres. It is generally accepted that recruitment of Type II fibres requires more intensive training, possibly requiring greater oxygen demand. However research has shown that the pedaling frequency of cycling can contribute to the pattern of fibre-type glycogen depletion without increasing oxygen demand. Cycling at 50, rather than 100 rpm (revolutions per minute), has been shown to result in a higher percentage of Type II fibre glycogen depletion despite a constant metabolic cost. This present study was conducted to determine whether training at a low cycle rate (45-50 rpm - revolutions per minute) would improve the power output at the LT (4 mmol/L fixed blood lactate concentration) in previously untrained university students. A total of 12 previously untrained university students (5 male, 7 female; age: 18.6 ± 0.67 years, height: 1.63 ± 0.06 metres, mass: 62.7 ± 6.52 kg) agreed to participate in this study and underwent a six-week training programme consisting of 3 x one-hour sessions per week on a Monark cycle ergometer. The cycle cadence I pedaling rate was maintained at 45-50 rpm in conjunction with a heart rate 120-130 bpm (beats per minute). All subjects completed a stage-graded ergometer lactate test, both before, and after undergoing a six-week training period. The group mean power output (watts) at the LT (4 mmol /L blood lactate) was improved by 17.3% in the post-training test. The result was highly significant to the 99% confidence level (p< 0.001). The conclusion is that the training method employed, with cycling cadence at 45-50 rpm, and heart rate between 120-130 bpm, is valid for improving the power output at the LT in previously untrained subjects under 21 years of age.