In this holistic review of cycling science, the objectives are: (1) to identify the various human and environmental factors that influence cycling power output and velocity; (2) to discuss, with the aid of a schematic model, the often complex interrelationships between these factors; and (3) to suggest future directions for research to help clarify how cycling performance can be optimized, given different race disciplines, environments and riders. Most successful cyclists, irrespective of the race discipline, have a high maximal aerobic power output measured from an incremental test, and an ability to work at relatively high power outputs for long periods. The relationship between these characteristics and inherent physiological factors such as muscle capilliarization and muscle fibre type is complicated by inter-individual differences in selecting cadence for different race conditions. More research is needed on high-class professional riders, since they probably represent the pinnacle of natural selection for, and physiological adaptation to, endurance exercise. Recent advances in mathematical modelling and bicycle-mounted strain gauges, which can measure power directly in races, are starting to help unravel the interrelationships between the various resistive forces on the bicycle (e.g. air and rolling resistance, gravity). Interventions on rider position to optimize aerodynamics should also consider the impact on power output of the rider. All-terrain bicycle (ATB) racing is a neglected discipline in terms of the characterization of power outputs in race conditions and the modelling of the effects of the different design of bicycle frame and components on the magnitude of resistive forces. A direct application of mathematical models of cycling velocity has been in identifying optimal pacing strategies for different race conditions. Such data should, nevertheless, be considered alongside physiological optimization of power output in a race. An even distribution of power output is both physiologically and biophysically optimal for longer ( > 4 km) time-trials held in conditions of unvarying wind and gradient. For shorter races (e.g. a 1 km time-trial), an 'all out' effort from the start is advised to 'save' time during the initial phase that contributes most to total race time and to optimize the contribution of kinetic energy to race velocity. From a biophysical standpoint, the optimum pacing strategy for road time-trials may involve increasing power in headwinds and uphill sections and decreasing power in tailwinds and when travelling downhill. More research, using models and direct power measurement, is needed to elucidate fully how much such a pacing strategy might save time in a real race and how much a variable power output can be tolerated by a rider. The cyclist's diet is a multifactorial issue in itself and many researchers have tried to examine aspects of cycling nutrition (e.g. timing, amount, composition) in isolation. Only recently have researchers attempted to analyse interrelationships between di...

The aim of this study was to determine the effects of caffeine ingestion on a 'preloaded' protocol that involved cycling for 2 min at a constant rate of 100% maximal power output immediately followed by a 1-min 'all-out' effort. Eleven male cyclists completed a ramp test to measure maximal power output. On two other occasions, the participants ingested caffeine (5 mg. kg(-1)) or placebo in a randomized, double-blind procedure. All tests were conducted on the participants' own bicycles using a Kingcycle test rig. Ratings of perceived exertion (RPE; 6-20 Borg scale) were lower in the caffeine trial by approximately 1 RPE point at 30, 60 and 120 s during the constant rate phase of the preloaded test (P <0.05). The mean power output during the all-out effort was increased following caffeine ingestion compared with placebo (794+/-164 vs 750+/-163 W; P=0.05). Blood lactate concentration 4, 5 and 6 min after exercise was also significantly higher by approximately 1 mmol. l(-1) in the caffeine trial (P <0.05). These results suggest that high-intensity cycling performance can be increased following moderate caffeine ingestion and that this improvement may be related to a reduction in RPE and an elevation in blood lactate concentration.

The results show that PPO affords a valid and reliable measure of endurance performance which can be used to predict average power during a 16.1-km TT but not performance time.

The purpose of this study was to assess reliability of both indoor and outdoor 40 km time-trial cycling performance. Eight trained cyclists completed three indoor 40 km time-trials on an air-braked ergometer (Kingcycle) and three outdoor 40 km time-trials on a local course. Power output was measured for all trials using the SRM powermeter. Mean performance time across three indoor trials was 54.21 +/- 2.59 (min:sec) and was significantly different (P<0.05) to mean time across three outdoor trials (57.29 +/- 3.22 min:sec). However, there was no significant difference (P = 0.34) for mean power across three indoor trials (303+/-35W) when compared to outdoor performances (312 +/- 23 W). Within-subject variation for mean power output expressed as a coefficient of variation (CV) improved in both indoors and outdoors for trials 2 and 3 (CV = 1.9%, 95% CI 1.0 - 3.4 and CV = 2.1 %, 95 % CI 1.1 - 3.8) when compared to trials 1 and 2 (CV=2.1%, 95% CI 1.2-3.8 and CV=2.4%, 95% CI 1.3-4.3). These findings indicate that power output measured using the SRM powermeter is highly reproducible for both laboratory-based and actual 40 km time-trial cycling performance.

Fifty-six subjects (19 men and 37 woman) aged between 40 and 66 completed the study. They were allocated into three walking groups and a control group (C). The three walking groups performed the same total amount of walking for 18 weeks, but completed it in bouts of differing durations and frequencies. These were Long Walkers (LW; 20-40 min/bout), Intermediate Walkers (IW; 10-15 min/bout) and Short Walkers (SW; 5-10 min/bout); with the IW and SW performing more than one bout of walking a day. Following the 18 week walking programme, compared to the C group all walking groups showed similar improvements in fitness as determined by a reduction in blood lactate during a graded treadmill walking test (LW 1.0 mmol/l; IW 0. 8 mmol/l; SW 1.2 mmol/l; C 0.2 mmol/l; P = 0.003) and reduction in final heart rate (LW 8 beats/min; IW 6 beats/min; SW 10 beats/min; C 0 beats/min; P = 0.056). Also compared to the C group, the LW and IW groups recorded statistically significant decreases in low-density lipoprotein cholesterol (LW 0.29 mmol/l; IW 0.41 mmol/l; P = 0.024), whereas the control group showed a mean increase of 0.22 mmol/l. The LW and IW groups also showed significant reductions in apolipoprotein (apo) A-II (LW 0.05 g/l; IW 0.02 g/l; SW 0.01 g/l; C 0.00 g/l; P = 0.012) with the LW recording a statistically significant increase in the ratio of apo A-I/A-II (LW, 0.19, P = 0. 044). In conclusion, some health benefits were achieved from all walking programmes. However, whilst the changes in aerobic fitness were similar, the effects upon blood lipid profiles were not. The findings from this study suggest that the LW regimen was most effective in benefiting blood lipid profile, followed by the IW regimen, with the SW being least potent. Nevertheless, for the sedentary/low-active members of society, any improvement in health may be considered as important. Therefore accumulated bouts of moderate intensity exercise, which according to theories of exercise behaviour may be more easily incorporated into an individual's lifestyle than single prolonged bouts, may be advocated for health promotion but may not be as effective as the traditionally prescribed 20-40 min bouts.