Irvin E. Faria

The Science of Cycling Physiology and Training - Part 1

AbstractThe aim of this review is to provide greater insight and understanding regarding the scientific nature of cycling. Research findings are presented in a practical manner for their direct application to cycling. The two parts of this review provide information that is useful to athletes, coaches and exercise scientists in the prescription of training regimens, adoption of exercise protocols and creation of research designs.Here for the first time, we present rationale to dispute prevailing myths linked to erroneous concepts and terminology surrounding the sport of cycling. In some studies, a review of the cycling literature revealed incomplete characterisation of athletic performance, lack of appropriate controls and small subject numbers, thereby complicating the understanding of the cycling research. Moreover, a mixture of cycling testing equipment coupled with a multitude of exercise protocols stresses the reliability and validity of the findings.Our scrutiny of the literature revealed key cycling performance-determining variables and their training-induced metabolic responses. The review of training strategies provides guidelines that will assist in the design of aerobic and anaerobic training protocols. Paradoxically, while maximal oxygen uptake (VO2max) is generally not considered a valid indicator of cycling performance when it is coupled with other markers of exercise performance (e.g. blood lactate, power output, metabolic thresholds and efficiency/economy), it is found to gain predictive credibility.The positive facets of lactate metabolism dispel the ‘lactic acid myth’. Lactate is shown to lower hydrogen ion concentrations rather than raise them, thereby retarding acidosis. Every aspect of lactate production is shown to be advantageous to cycling performance. To minimise the effects of muscle fatigue, the efficacy of employing a combination of different high cycling cadences is evident. The subconscious fatigue avoidance mechanism ‘teleoanticipation’ system serves to set the tolerable upper limits of competitive effort in order to assure the athlete completion of the physical challenge.Physiological markers found to be predictive of cycling performance include: (i) power output at the lactate threshold (LT2); (ii) peak power output (Wpeak) indicating a power/weight ratio of ≥5.5 W/kg; (iii) the percentage of type I fibres in the vastus lateralis; (iv) maximal lactate steady-state, representing the highest exercise intensity at which blood lactate concentration remains stable; (v) Wpeak at LT2; and (vi) Wpeak during a maximal cycling test. Furthermore, the unique breathing pattern, characterised by a lack of tachypnoeic shift, found in professional cyclists may enhance the efficiency and metabolic cost of breathing. The training impulse is useful to characterise exercise intensity and load during training and competition. It serves to enable the cyclist or coach to evaluate the effects of training strategies and may well serve to predict the cyclist’s performance.Findings indicate that peripheral adaptations in working muscles play a more important role for enhanced submaximal cycling capacity than central adaptations. Clearly, relatively brief but intense sprint training can enhance both glycolytic and oxidative enzyme activity, maximum short-term power output and VO2max. To that end, it is suggested to replace ~15% of normal training with one of the interval exercise protocols. Tapering, through reduction in duration of training sessions or the frequency of sessions per week while maintaining intensity, is extremely effective for improvement of cycling time-trial performance. Overuse and over-training disabilities common to the competitive cyclist, if untreated, can lead to delayed recovery.

The Science of Cycling Factors Affecting Performance - Part 2

AbstractThis review presents information that is useful to athletes, coaches and exercise scientists in the adoption of exercise protocols, prescription of training regimens and creation of research designs. Part 2 focuses on the factors that affect cycling performance. Among those factors, aerodynamic resistance is the major resistance force the racing cyclist must overcome. This challenge can be dealt with through equipment technological modifications and body position configuration adjustments. To successfully achieve efficient transfer of power from the body to the drive train of the bicycle the major concern is bicycle configuration and cycling body position. Peak power output appears to be highly correlated with cycling success. Likewise, gear ratio and pedalling cadence directly influence cycling economy/efficiency. Knowledge of muscle recruitment throughout the crank cycle has important implications for training and body position adjustments while climbing. A review of pacing models suggests that while there appears to be some evidence in favour of one technique over another, there remains the need for further field research to validate the findings. Nevertheless, performance modelling has important implications for the establishment of performance standards and consequent recommendations for training.

Energy Expenditure, Aerodynamics and Medical Problems in Cycling: An Update

SummaryThe cyclist’s ability to maintain an extremely high rate of energy expenditure for long durations at a high economy of effort is dependent upon such factors as the individual’s anaerobic threshold, muscle fibre type, muscle myoglobin concentration, muscle capillary density and certain anthropometric dimensions. Although laboratory tests have had some success predicting cycling potential, their validity has yet to be established for trained cyclists. Even in analysing the forces producing propulsive torque, cycling effectiveness cannot be based solely on the orientation of applied forces.Innovations of shoe and pedal design continue to have a positive influence on the biomechanics of pedalling. Although muscle involvement during a complete pedal revolution may be similar, economical pedalling rate appears to differ significantly between the novice and racing cyclist. This difference emanates, perhaps, from long term adaptation.Air resistance is by far the greatest retarding force affecting cycling. The aerodynamics of the rider and the bicycle and its components are major contributors to cycling economy. Correct body posture and spacing between riders can significantly enhance speed and efficiency.Acute and chronic responses to cycling and training are complex. To protect the safety and health of the cyclist there must be close monitoring and cooperation between the cyclist, coach, exercise scientist and physician.

Circadian changes in resting heart rate and body temperature, maximal oxygen consumption and perceived exertion

To investigate the existence, magnitude and interplay of rhythmic 24-hour variations in human functions, maximal O2 uptake (VO2max), resting heart rate (ƒH), body temperature (Tb) and rated perceived exertion (RPE) during exercise were measured twice every 2hours over a full day-night cycle. Thirty-one subjects were randomly administered a treadmill test on 24 separate occasions, 48 hours apart. RPE was observed at heart rates of 130, 150 and 170beats/min. Resting T b, and/H were lower (p< 005) in the morning than afternoon or evening. Measurement of [Vdot]O2 max revealed no significant differences throughout 24 hours. RPE was higher (p< 0-05)at 130, 150 and 170HR at 02.00 and 04.00hours than at 20.00, 22.00 and 24.00 hours. T b and ƒH were apparently in phase.and show a sine wave pattern when expressed on a 24-hour scale. These data demonstrate the significance of the circadian variation for the application of functional tests.

Applied Physiology of Cycling

SummaryHistorically, the bicycle has evolved through the stages of a machine for efficient human transportation, a toy for children, a finely-tuned racing machine, and a tool for physical fitness development, maintenance and testing. Recently, major strides have been made in the aerodynamic design of the bicycle. These innovations have resulted in new land speed records for human powered machines.Performance in cycling is affected by a variety of factors, including aerobic and anaerobic capacity, muscular strength and endurance, and body composition. Bicycle races range from a 200m sprint to approximately 5000km. This vast range of competitive racing requires special attention to the principle of specificity of training.The physiological demands of cycling have been examined through the use of bicycle ergometers, rollers, cycling trainers, treadmill cycling, high speed photography, computer graphics, strain gauges, electromyography, wind tunnels, muscle biopsy, and body composition analysis. These techniques have been useful in providing definitive data for the development of a work/performance profile of the cyclist.Research evidence strongly suggests that when measuring the cyclist’s aerobic or anaerobic capacity, a cycling protocol employing a high pedalling rpm should be used. The research bicycle should be modified to resemble a racing bicycle and the cyclist should wear cycling shoes. Prolonged cycling requires special nutritional considerations. Ingestion of carbohydrates, in solid form and carefully timed, influences performance. Caffeine appears to enhance lipid metabolism.Injuries, particularly knee problems which are prevalent among cyclists, may be avoided through the use of proper gearing and orthotics. Air pollution has been shown to impair physical performance. When pollution levels are high, training should be altered or curtailed.Effective training programmes simulate competitive conditions. Short and long interval training, blended with long distance tempo cycling, will exploit both the anaerobic and aerobic systems. Strength training, to be effective, must be performed with the specific muscle groups used in cycling, and at specific angles of involvement.

Influence of leg preference on bilateral muscle activation during cycling

Abstract The purpose of this study was to investigate asymmetry of muscle activation in participants with different levels of experience and performance with cycling. Two separate experiments were conducted, one with nine cyclists and one with nine non-cyclists. The experiments involved incremental maximal and sub-maximal constant load cycling tests. Bilateral surface electromyography (EMG) and gross and net muscle efficiency were assessed. Analyses of variance in mixed linear models and t-tests were conducted. The cyclists in Experiment 1 presented higher gross efficiency (P < 0.05), whereas net efficiency did not differ between the two experiments (21.3 ± 1.4% and 19.8 ± 1.0% for cyclists and non-cyclists, respectively). The electrical muscle activity increased significantly with exercise intensity regardless of leg preference in both experiments. The coefficient of variation of EMG indicated main effects of leg in both experiments. The non-preferred leg of non-cyclists (Experiment 2) presented statistically higher variability of muscle activity in the gastrocnemius medialis and vastus lateralis. Our findings suggest similar electrical muscle activity between legs in both cyclists and non-cyclists regardless of exercise intensity. However, EMG variability was asymmetric and appears to be strongly influenced by exercise intensity for cyclists and non-cyclists, especially during sub-maximal intensity. Neural factors per se do not seem to fully explain previous reports of pedalling asymmetries.

Nasal splinting effects on breathing patterns and cardiorespiratory responses

The aim of this study was to compare the effects of nasal splinting during different modes of breathing on breathing patterns and cardiorespiratory responses. Ten healthy subjects (4 males, 6 females) performed five maximal treadmill tests while breathing through the nose, nose + dilator, mouth, nose + mouth, and nose + mouth + dilator. Repeated-measures analysis of variance and Tukey HSD revealed no significant differences between trials for maximal oxygen consumption, minute ventilation at an oxygen consumption of 30 ml.kg-1.min-1, carbon dioxide production, respiratory exchange ratio, tidal volume, dead space to tidal volume ratio, or completed treadmill stages to exhaustion. No significant difference was found in subjective dyspnoea ratings between stages of nose versus nose + dilator breathing. Minute ventilation, ventilatory equivalent for oxygen, and breath frequency for nose and nose + dilator versus mouth, nose + mouth, and nose + mouth + dilator were significantly lower. Ventilatory equivalent for carbon dioxide was significantly lower for nose versus mouth, and nose + dilator versus nose + mouth + dilator breathing. End-tidal carbon dioxide was significantly higher in nose versus mouth, nose + mouth, and nose + mouth + dilator breathing, and in nose + dilator versus mouth breathing. Nose breathing revealed a significantly lower heart rate versus nose + dilator, mouth, nose + mouth, and nose + mouth + dilator breathing. These results suggest that nasal splinting during exercise has minimal effects when nasal breathing and no effects when oronasal breathing.

Cardiorespiratory responses to exercises of equal relative intensity distributed between the upper and lower body

The principles underlying the cardiorespiratory responses to upper body versus lower body exercise remain unclear. We explored the hypothesis that workloads of the same percentage of maximum strength for a particular part of the body might elicit similar cardiovascular responses. Twelve trained female university rowers (mean +/- s: age, 22.8 +/- 1.3 years; body mass, 66.9 +/- 1.8 kg; height, 169 +/- 6 cm; body fat, 18 +/- 2%; HRpeak, 190 +/- 3 beats min(-1); VO2 peak, 50.7 +/- 2.6 ml kg(-1) min(-1)) performed four 12 min exercise trials on a rowing ergometer. Arm rowing, leg extension and arm rowing + leg extension workloads were set at 20% of the mean of their respective three-repetition maximum (3-RM). The combination of arm rowing and leg extension was also performed in a reciprocal workload fashion; that is, the arm workload was 20% of the mean 3-RM for leg extension, and the leg extension workload was 20% of the mean 3-RM for arm rowing. Analysis of variance and Tukey HSD showed that, although the power output for leg extension was 144% higher than for arm rowing, the mean VO2, VE and heart rate values were not significantly different between exercise modes. Oxygen uptake for reciprocal arm rowing + leg extension, with the arms performing 71% of the total power output, was not significantly different from non-reciprocal arm rowing + leg extension; however, the VE and heart rate values were higher. Our results suggest that, during submaximal exercise, cardiorespiratory responses to upper body exercise do not differ significantly from those to lower body exercise, so long as the upper and lower body workloads are set at an equal relative strength level.

Does leg preference affect muscle activation and efficiency

The aim of this study was to investigate the effect of leg preference and cycling experience on unilateral muscle efficiency and muscle activation. To achieve this purpose, two experiments were performed. Experiment 1 involved eight cyclists and experiment 2 included eight non-cyclists. Subjects underwent an incremental maximal test and submaximal trials of one-legged cycling for preferred and non-preferred leg. Oxygen uptake and muscle efficiency were compared between legs. The magnitude of muscle activation (RMS) and the inter-limb excitation were monitored for the vastus lateralis, biceps femoris and gastrocnemius (medial head) muscles during one-legged cycling with preferred and non-preferred leg. Variables of muscle activation, oxygen uptake and muscle efficiency (gross and net) did not differ between legs (P>0.05). The magnitude of muscle activation and its variability were similar between legs while performing the unilateral pedaling. Inter-limb communication did not differ between experiments (P>0.05). Similar activation between legs was consistent with the influence of bilateral practice for attaining similar performance between sides. These results do not support asymmetry in magnitude of muscle activation during pedaling.

Ventilatory response pattern of Nordic skiers during simulated poling

Cross-country ski poling is a distinctive exercise imposed by biomechanical motion which may influence the breathing pattern. To examine the ventilatory patterns of competitive cross-country skiers, the pulmonary function of nine male master level skiers was studied during simulated bilateral synchronous and asynchronous arm poling and upright leg cycling. Physiological and ventilatory responses during arm and leg exercise were compared on a Biokinetic arm ergometer and Monark bicycle. At similar levels of oxygen consumption, minute ventilation (VE) was lower for leg cycling than for the arm exercise modes. Heart rate was significantly higher (P < 0.05) during bilateral synchronous poling than for either bilateral asynchronous poling or leg cycling. Leg cycling elicited a higher tidal volume (VT) than either of the arm poling modes (1.8 vs 1.7 and 1.6 l). Breathing frequency (fR) was significantly higher (P < 0.05) for both arm exercise modes when compared to leg cycling (41 and 42 vs 27 breaths min-1). Frequency of strokes per breath (fS/fR) was significantly higher (P < 0.01) while cycling compared to synchronous arm work. The mean ratio of fS/fR per minute was 1.1:1 and 1.7:1 for arm exercise and leg cycling, respectively. Bilateral synchronous arm poling invoked a similar VE, lower VT and higher fR than bilateral asynchronous poling or leg cycling. These results demonstrate that ventilatory responses to arm poling are different from those to upright cycle exercise. There was a greater reliance during poling upon fR to maintain VE.