Low Cadence Research Articles

Maximizing muscle force via low-cadence functional electrical stimulation cycling

This study investigated the effect of pedal cadence upon torque production, power output and muscle fatigue rates during functional electrical stimulation evoked cycling in spinal cord injured individuals. All subjects had complete thoracic spinal cord injuries T4-T9 (ASIA A) and had been functional electrical stimulation training regularly for at least 6 months. One trial (n = 8) examined a low vs high pedal rate (20 and 50 rev x min(-1)) upon isolated muscle fatigue over 5 minutes. A second trial (n = 9) investigated the effect of cadence (15 vs 50 rev x min(-1)) upon performance during 35-minutes of functional electrical stimulation evoked cycling. Peak torque produced by left quadriceps decayed significantly faster at the higher pedal cadence, indicating a higher rate of muscle fatigue. Functional electrical stimulation cycling over 35 minutes also revealed that peak and average torques were significantly greater at the lower cadence. From 15 minutes onwards, power output was significantly higher at 50 rev x min(-1) FES-cycling, compared with 15 rev x min(-1). The higher muscle forces observed during low cadence functional electrical stimulation cycling should offer improvements over traditional pedalling velocities for training leg strength in individuals with spinal cord injury.

In professional road cyclists, low pedaling cadences are less efficient.

To determine the effects of changes in pedaling frequency on the gross efficiency (GE) and other physiological variables (oxygen uptake (VO2), HR, lactate, pH, ventilation, motor unit recruitment estimated by EMG) of professional cyclists while generating high power outputs (PO). Following a counterbalanced, cross-over design, eight professional cyclists (age (mean +/- SD): 26 +/- 2 yr, VO2max: 74.0 +/- 5.7 mL x kg x min) performed three 6-min bouts at a fixed PO (mean of 366 +/- 37 W) and at a cadence of 60, 80, and 100 rpm. Values of GE averaged 22.4 +/- 1.7, 23.6 +/- 1.8 and 24.2 +/- 2.0% at 60, 80, and 100 rpm, respectively. Mean GE at 100 rpm was significantly higher than at 60 rpm (P < 0.05). Similarly, mean values of VO2, HR, rates of perceived exertion (RPE), lactate and normalized root-mean square EMG (rms-EMG) in both vastus lateralis and gluteus maximum muscles decreased at increasing cadences. In professional road cyclists riding at high PO, GE/economy improves at increasing pedaling cadences.

Development of an Isokinetic Functional Electrical Stimulation Cycle Ergometer

An isokinetic functional electrical stimulation leg cycle ergometer (iFES-LCE) was developed for individuals with spinal cord injury (SCI). The iFES-LCE was designed to allow cycle training over a broad range of pedalling cadences (5-60 rev/min) to promote both muscular strength and cardiorespiratory fitness. A commercially available motorized cycle ergometer was integrated with a custom built FES system, a laptop computer, and a specialized chair that restricted lateral leg movements. Sample biomechanical data were collected from an SCI subject performing FES cycling to demonstrate the iFES-LCE's performance characteristics. Calibration of the iFES-LCE system revealed a linear relationship between torque applied to the axle of the motorized ergometer and the braking motor current generated to maintain velocity. Performance data derived from iFES-LCE motor torque agreed closely with similar data collected using strain-gauge instrumented pedals (cross-correlations =0.93-0.98). The iFES-LCE was shown to work well across a range of pedaling cadences. We conclude that the new iFES-LCE system may offer improved training potential by allowing cycling over a broad range of pedaling cadences, especially low cadence. This device also improves upon the accuracy of other ergometers by adjusting for the passive load of the legs.

Gear, inertial work and road slopes as determinants of biomechanics in cycling.

In cycling the gear determines the distance travelled and the mean applied force at each leg thrust. According to Padilla et al. (J Appl Physiol 89:1522-1527, 2000), an elite cyclist was able to cycle for an hour at 14.6 m.s(-1 developing 510 W at a pedal frequency of 101 rpm. Thus, the opposing force was 34 N (=500/14.6), whereas the mean force, developed by the leg muscles, was 144.1 N. It can be calculated that in the same subject cycling on a 20% slope at the same pedal frequency, the velocity would be reduced by about 5 times, i.e. to 2.9 m.s(-1) because of a fivefold increase of the opposing force. In reality, the increase of mean force developed by leg muscles is even larger, because of the fall of the cadence to 60 rpm. In general, during mountain ascents cyclists develop high forces at low cadences that are likely to be more economical; in contrast, on flat ground, they increase the pedalling rates because their aerodynamic posture does not allow high force production. The intermittent pattern of muscular force application generates speed changes that become more evident at great inclines and low cadences. It can be shown that inertial work is appreciable in cycling, increasing with the incline of the road and decreasing with the cadence. However, inertial work does not seem to affect efficiency. Differences in physiologic potential make differences in performance more evident in time trials where the mean incline of the road is not negligible. Cyclists with low body size have an advantageous force versus mass ratio in high mountain ascents.

THE EFFECT OF CYCLE CADENCE ON A HEART RATE BASED TRAINING PROGRAM921

The purpose of this study was to determine the effect of cycling cadence during 8 weeks of heart rate (HR) based training on peak watts (WPeak) and peak aerobic capacity (VO2peak). Sixteen sedentary adult females agreed to participate in a 22 week, cross-over design, training study, with random assignment to: Group A, [8wks at low cadence (LC=60 rpm), 6wks no training (“washout”), 8 wks at high cadence (HC=80 rpm)]; or Group B [8wks at HC, 6wks no training (“washout”), 8 wks at LC. Subjects performed a graded exercise test to volitional exhaustion to determine VO2peak and Wpeak before and after each 8 week training period. Training was 3 times/week for 30 minutes at the HR associated with 70% of pre-training VO2peak. We found a significant (p<.05) pre-to-post training increase in VO2peak and Wpeak at both LC[VO2peak:206±66 (mean±S.E.) ml O2/min; Wpeak 24.7±4.3 watts], and HC [VO2peak: 212±45 ml O2/min; Wpeak 15.0±3.6 watts]. However, neither VO2peak nor Wpeak showed a significant difference in training improvement between LC and HC, even though the cross over design gave us a 95% chance of detecting a cadence effect as small as 277 ml O2/min (VO2peak) or 23 watts (Wpeak). Our results, from sedentary women, suggested that cycling cadence during an 8-week heart rate-based training program has no effect on the improvement in peak watts and peak aerobic capacity.

Effect of cadence on the economy of uphill cycling

Competitive cyclists generally climb hills at a low cadence despite the recognized advantage in level cycling of high cadences. To test whether a high cadence is more economical than a low cadence during uphill cycling, nine experienced cyclists performed steady-state bicycling exercise on a treadmill under three randomized trials. Subjects bicycled at 11.3 km.h-1 up a 10% grade while 1) pedalling at 84 rpm in a sitting position-84 Sit, 2) pedalling at 41 rpm in a standing position-41 Stand, and 3) pedalling at 41 rpm in a sitting position-41 Sit. Heart rate (HR), oxygen consumption (VO2), ventilation (VE), and respiratory exchange ratio were measured continuously during 5-min trials and averaged over the last 2 min. Additionally, rating of perceived exertion was recorded during the fifth minute of each trial, and blood lactate concentration was recorded immediately before and after each trial. Significantly lower values for HR, VO2 and VE were recorded during 84 Sit (164 +/- 3 bpm, 51.8 +/- 0.8 ml.min-1 x kg-1, 94 +/- 5 l.min-1) than for either the 41 Stand (171 +/- 2 bpm, 53.1 +/- 0.7 ml.min-1 x kg-1, 105 +/- 6 l.min-1) o 41 Sit (168 +/- 2 bpm, 53.1 +/- 0.8 ml.min-1 x kg-1, 101 +/- 6 l.min-1) trials. No other differences were noted between trials for any of the measured variables. We conclude that uphill cycling is more economical at a high versus a low cadence.

Physiological actions of taurine

Physiological actions of taurine