The Science of Cycling

Long-term Low-to-Intensive Cycling Training: Impact on Semen Parameters and Seminal Cytokines

OBJECTIVE

To examine the effects of long-term low-to-intensive cycling training on seminal cytokines and semen parameters in male road cyclists.

DESIGN

Repeated measures design.

SETTING

The Exercise Physiology Laboratory of the Urmia University.

PARTICIPANTS

Twenty-four healthy nonprofessional male road cyclists (23.1 ± 6.2 years) participated in this study.

INTERVENTIONS

All subjects participated in a 16-week low-to-intensive cycling training. The semen samples were collected, respectively, at baseline (T1), immediately (T2), 12 (T3), and 24 (T4) hours after the last training session in week 8; immediately (T5), 12 (T6), and 24 (T7) hours after the last training session in week 16; as well as 7 (T8) and 30 (T9) days after the last training session in week 16.

MAIN OUTCOME MEASURES

Semen volume, sperm motility, sperm morphology, sperm concentration, and number of spermatozoa as well as seminal interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor-α in seminal plasma from male road cyclists.

RESULTS

The levels of seminal IL-1β, IL-6, and IL-8 increased (P < 0.008) and remained high after 30 days of recovery. Semen volume, sperm motility, sperm morphology, sperm concentration, and number of spermatozoa decreased (P < 0.008). All of the above-mentioned variables (with the exception of semen volume, sperm motility, and sperm concentration) remained low after 30 days of recovery (P < 0.008).

CONCLUSIONS

A 16-week low-to-intensive cycling training may have deleterious consequences for spermatozoa and hence may have an impact on male fertility among cyclists.

CLINICAL RELEVANCE

Given that exercise can affect reproductive system among male cyclists, hence cyclists may routinely employ sufficient rest after their training sessions to ensure that the sperm healthy parameters and seminal immunological profiles have properly recovered from the last training sessions.

The science of badminton: game characteristics, anthropometry, physiology, visual fitness and biomechanics

Badminton is a racket sport for two or four people, with a temporal structure characterized by actions of short duration and high intensity. This sport has five events: men's and women's singles, men's and women's doubles, and mixed doubles, each requiring specific preparation in terms of technique, control and physical fitness. Badminton is one of the most popular sports in the world, with 200 million adherents. The decision to include badminton in the 1992 Olympics Game increased participation in the game. This review focuses on the game characteristics, anthropometry, physiology, visual attributes and biomechanics of badminton. Players are generally tall and lean, with an ectomesomorphic body type suited to the high physiological demands of a match. Indeed, a typical match characteristic is a rally time of 7 s and a resting time of 15 s, with an effective playing time of 31%. This sport is highly demanding, with an average heart rate (HR) of over 90% of the player's maximal HR. The intermittent actions during a game are demanding on both the aerobic and anaerobic systems: 60-70% on the aerobic system and approximately 30% on the anaerobic system, with greater demand on the alactic metabolism with respect to the lactic anaerobic metabolism. The shuttlecock has an atypical trajectory, and the players perform specific movements such as lunging and jumping, and powerful strokes using a specific pattern of movement. Lastly, badminton players are visually fit, picking up accurate visual information in a short time. Knowledge of badminton can help to improve coaching and badminton skills.

Long-Term Endurance Exercise in Humans Stimulates Cell Fusion of Myoblasts along with Fusogenic Endogenous Retroviral Genes In Vivo

Myogenesis is defined as growth, differentiation and repair of muscles where cell fusion of myoblasts to multinucleated myofibers is one major characteristic. Other cell fusion events in humans are found with bone resorbing osteoclasts and placental syncytiotrophoblasts. No unifying gene regulation for natural cell fusions has been found. We analyzed skeletal muscle biopsies of competitive cyclists for muscle-specific attributes and expression of human endogenous retrovirus (ERV) envelope genes due to their involvement in cell fusion of osteoclasts and syncytiotrophoblasts. Comparing muscle biopsies from post- with the pre-competitive seasons a significant 2.25-fold increase of myonuclei/mm fiber, a 2.38-fold decrease of fiber area/nucleus and a 3.1-fold decrease of satellite cells (SCs) occurred. We propose that during the pre-competitive season SC proliferation occurred following with increased cell fusion during the competitive season. Expression of twenty-two envelope genes of muscle biopsies demonstrated a significant increase of putative muscle-cell fusogenic genes Syncytin-1 and Syncytin-3, but also for the non-fusogenic erv3. Immunohistochemistry analyses showed that Syncytin-1 mainly localized to the sarcolemma of myofibers positive for myosin heavy-chain isotypes. Cellular receptors SLC1A4 and SLC1A5 of Syncytin-1 showed significant decrease of expression in post-competitive muscles compared with the pre-competitive season, but only SLC1A4 protein expression localized throughout the myofiber. Erv3 protein was strongly expressed throughout the myofiber, whereas envK1-7 localized to SC nuclei and myonuclei. Syncytin-1 transcription factors, PPARγ and RXRα, showed no protein expression in the myofiber, whereas the pCREB-Ser133 activator of Syncytin-1 was enriched to SC nuclei and myonuclei. Syncytin-1, Syncytin-3, SLC1A4 and PAX7 gene regulations along with MyoD1 and myogenin were verified during proliferating or actively-fusing human primary myoblast cell cultures, resembling muscle biopsies of cyclists. Myoblast treatment with anti-Synycytin-1 abrogated cell fusion in vitro. Our findings support functional roles for ERV envelope proteins, especially Syncytin-1, contributing to cell fusion of myotubes.

Inorganic nitrate supplementation improves muscle oxygenation, O₂ uptake kinetics, and exercise tolerance at high but not low pedal rates

We tested the hypothesis that inorganic nitrate (NO3 (-)) supplementation would improve muscle oxygenation, pulmonary oxygen uptake (V̇o2) kinetics, and exercise tolerance (Tlim) to a greater extent when cycling at high compared with low pedal rates. In a randomized, placebo-controlled cross-over study, seven subjects (mean ± SD, age 21 ± 2 yr, body mass 86 ± 10 kg) completed severe-intensity step cycle tests at pedal cadences of 35 rpm and 115 rpm during separate nine-day supplementation periods with NO3 (-)-rich beetroot juice (BR) (providing 8.4 mmol NO3 (-)/day) and placebo (PLA). Compared with PLA, plasma nitrite concentration increased 178% with BR (P < 0.01). There were no significant differences in muscle oxyhemoglobin concentration ([O2Hb]), phase II V̇o2 kinetics, or Tlim between BR and PLA when cycling at 35 rpm (P > 0.05). However, when cycling at 115 rpm, muscle [O2Hb] was higher at baseline and throughout exercise, phase II V̇o2 kinetics was faster (47 ± 16 s vs. 61 ± 25 s; P < 0.05), and Tlim was greater (362 ± 137 s vs. 297 ± 79 s; P < 0.05) with BR compared with PLA. These results suggest that short-term BR supplementation can increase muscle oxygenation, expedite the adjustment of oxidative metabolism, and enhance exercise tolerance when cycling at a high, but not a low, pedal cadence in healthy recreationally active subjects. These findings support recent observations that NO3 (-) supplementation may be particularly effective at improving physiological and functional responses in type II muscle fibers.

Lack of Association Between ACE Indel Polymorphism and Cardiorespiratory Fitness in Physically Active and Sedentary Young Women

Background:

Polymorphisms at the angiotensin-converting enzyme gene (ACE), such as the indel [rs1799752] variant in intron 16, have been shown to be associated with aerobic performance of athletes and non-athletes. However, the relationship between ACE indel polymorphism and cardiorespiratory fitness has not been always demonstrated.

Objectives:

The relationship between ACE indel polymorphism and cardiorespiratory fitness was investigated in a sample of young Caucasian Brazilian women.

Patients and Methods:

This study investigated 117 healthy women (aged 18 to 30 years) who were grouped as physically active (n = 59) or sedentary (n = 58). All subjects performed an incremental exercise test (ramp protocol) on a cycle-ergometer with 20-25 W/min increments. Blood samples were obtained for DNA extraction and to analyze metabolic and hormonal profiles. ACE indel polymorphism was determined by polymerase chain reaction (PCR) and fragment size analysis.

Results:

The physically active group had higher values of peak oxygen uptake (VO₂ peak), carbon dioxide output (VCO₂), ventilation (VE) and power output than the sedentary group (P < 0.05) at the peak of the exercise test. However, heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) did not differ between groups. There was no relationship between ACE indel polymorphism and cardiorespiratory variables during the test in both the physically active and sedentary groups, even when the dominant (DD vs. D1 + 2) and recessive (2 vs. DI + DD) models of inheritance were tested.

Conclusions:

These results do not support the concept that the genetic variation at the ACE locus contributes to the cardiorespiratory responses at the peak of exercise test in physically active or sedentary healthy women. This indicates that other factors might mediate these responses, including the physical training level of the women.

The effects of 16 weeks of intensive cycling training on seminal oxidants and antioxidants in male road cyclists

OBJECTIVE

To examine the effects of 16 weeks of intensive cycling training on seminal reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), catalase, and total antioxidant capacity (TAC) in male road cyclists.

DESIGN

Repeated measures design.

SETTING

The Exercise Physiology Laboratory of the Urmia University.

PARTICIPANTS

Twenty-four healthy nonprofessional male road cyclists (aged 17-26 years) participated in this study.

INTERVENTIONS

All subjects participated in 16 weeks of intensive cycling training. The semen samples were collected, respectively, at baseline (T1), immediately (T2), 12 (T3), and 24 (T4) hours after the last training session in week 8; immediately (T5), 12 (T6), and 24 (T7) hours after the last training session in week 16; and 7 (T8) and 30 (T9) days after the last training session in week 16.

MAIN OUTCOME MEASURES

Total antioxidant capacity and SOD were measured by colorimetric assay. The levels of ROS were measured by a chemiluminescence assay. Malondialdehyde levels were measured by thiobarbituric acid reactive substance assay. Catalase was measured by monitoring the initial rate of disappearance of hydrogen peroxide (initial concentration 10 mM) at 240 nm.

RESULTS

The levels of seminal ROS and MDA increased (P < 0.008) and remained high after 30 days of recovery. The levels of seminal SOD, catalase, and TAC decreased (P < 0.008) and remained low after 30 days of recovery (P < 0.008).

CONCLUSIONS

Sixteen weeks of intensive cycling training may have deleterious consequences for spermatozoa and hence may affect sperm healthy parameters in male cyclists.

Reliability of Physiological Attributes and Their Association With Stochastic Cycling Performance

Purpose:

To assess the reliability of a 5-min-stage graded exercise test (GXT) and determine the association between physiological attributes and performance over stochastic cycling trials of varying distance.

Methods:

Twenty-eight well-trained male cyclists performed 2 GXTs and either a 30-km (n = 17) or a 100-km stochastic cycling time trial (n = 9). Stochastic cycling trials included periods of high-intensity efforts for durations of 250 m, 1 km, or 4 km depending on the test being performing.

Results:

Maximal physiological attributes were found to be extremely reliable (maximal oxygen uptake [VO2max]: coefficient of variation [CV] 3.0%, intraclass correlation coefficient [ICC] .911; peak power output [PPO]: CV 3.0%, ICC .913), but a greater variability was found in ventilatory thresholds and economy. All physiological variables measured during the GXT, except economy at 200 W, were correlated with 30-km cycling performance. Power output during the 250-m and 1-km efforts of the 30-km trial were correlated with VO2max, PPO, and the power output at the second ventilatory threshold (r = .58–.82). PPO was the only physiological attributed measured during the GXT to be correlated with performance during the 100-km cycling trial (r = .64).

Conclusions:

Many physiological variables from a reliable GXT were associated with performance over shorter (30-km) but not longer (100-km) stochastic cycling trials.

Erythropoietin doping in cycling: lack of evidence for efficacy and a negative risk-benefit

Imagine a medicine that is expected to have very limited effects based upon knowledge of its pharmacology and (patho)physiology and that is studied in the wrong population, with low-quality studies that use a surrogate end-point that relates to the clinical end-point in a partial manner at most. Such a medicine would surely not be recommended. The use of recombinant human erythropoietin (rHuEPO) to enhance performance in cycling is very common. A qualitative systematic review of the available literature was performed to examine the evidence for the ergogenic properties of this drug, which is normally used to treat anaemia in chronic renal failure patients. The results of this literature search show that there is no scientific basis from which to conclude that rHuEPO has performance-enhancing properties in elite cyclists. The reported studies have many shortcomings regarding translation of the results to professional cycling endurance performance. Additionally, the possibly harmful side-effects have not been adequately researched for this population but appear to be worrying, at least. The use of rHuEPO in cycling is rife but scientifically unsupported by evidence, and its use in sports is medical malpractice. What its use would have been, if the involved team physicians had been trained in clinical pharmacology and had investigated this properly, remains a matter of speculation. A single well-controlled trial in athletes in real-life circumstances would give a better indication of the real advantages and risk factors of rHuEPO use, but it would be an oversimplification to suggest that this would eradicate its use.

Nonlinear exercise training in advanced chronic obstructive pulmonary disease is superior to traditional exercise training. A randomized trial

RATIONALE

The optimal exercise training intensity and strategy for individualized exercise training in chronic obstructive pulmonary disease (COPD) is not clear.

OBJECTIVES

This study compares the effects of nonlinear periodized exercise (NLPE) training used in athletes to traditional endurance and progressive resistance (EPR) training in patients with severe COPD.

METHODS

A total of 110 patients with severe COPD (FEV1 32% predicted) were randomized to EPR or NLPE. Exercise training was performed three times per week for 10 weeks. The primary outcomes were cycling endurance time and health-related quality of life using the Chronic Respiratory Questionnaire. The difference in change between EPR and NLPE was assessed using linear mixed-effects modeling.

MEASUREMENTS AND MAIN RESULTS

NLPE resulted in significantly greater improvements in cycling endurance time compared with EPR. The difference in change was +300.6 seconds (95% confidence interval [CI] = 197.2-404.2 s; P < 0.001). NLPE also resulted in significantly greater improvements in all domains of the Chronic Respiratory Questionnaire compared with EPR, ranging from +0.48 (95% CI = 0.19-0.78) for the domain, emotions, to +0.96 (95% CI = 0.57-1.35) for dyspnea.

CONCLUSIONS

NLPE results in greater improvements in cycle endurance and health-related quality of life in patients with severe COPD than traditional training methods. Clinical trial registered with www.trialregister.nl (The Netherlands Trial Register; NTR 1045).

Anaerobic power in road cyclists is improved after 10 weeks of whole-body vibration training

Whole-body vibration (WBV) training has previously improved muscle power in various athletic groups requiring explosive muscle contractions. To evaluate the benefit of including WBV as a training adjunct for improving aerobic and anaerobic cycling performance, road cyclists (n = 9) performed 3 weekly, 10-minute sessions of intermittent WBV on synchronous vertical plates (30 Hz) while standing in a static posture. A control group of cyclists (n = 8) received no WBV training. Before and after the 10-week intervention period, lean body mass (LBM), cycling aerobic peak power (Wmax), 4 mM lactate concentration (OBLA), VO2peak, and Wingate anaerobic peak and mean power output were determined. The WBV group successfully completed all WBV sessions but reported a significant 30% decrease in the weekly cycling training time (pre: 9.4 ± 3.3 h·wk(-1); post: 6.7 ± 3.7 h·wk(-1); p = 0.01) that resulted in a 6% decrease in VO2peak and a 4% decrease in OBLA. The control group reported a nonsignificant 6% decrease in cycling training volume (pre: 9.5 ± 3.6 h·wk(-1); 8.6 ± 2.9 h·wk(-1); p = 0.13), and all measured variables were maintained. Despite the evidence of detraining in the WBV group, Wmax was maintained (pre: 258 ± 53 W; post: 254 ± 57 W; p = 0.43). Furthermore, Wingate peak power increased by 6% (668 ± 189 to 708 ± 220 W; p = 0.055), and Wingate mean power increased by 2% (553 ± 157 to 565 ± 157 W; p = 0.006) in the WBV group from preintervention to postintervention, respectively, without any change to LBM. The WBV training is an attractive training supplement for improving anaerobic power without increasing muscle mass in road cyclists.

Temporal activity in particular segments and transitions in the olympic triathlon

The Olympic Triathlon is a combined endurance sport. It includes back-to-back swimming, cycling, running and the transition between events (T1 & T2). The aim of the current study was to analyse the possible relationship between the Lost Time T1 & T2 and overall performance. The results showed that the percentages of total time corresponding to each part of the race were: 16.2% for swimming, 0.74% for the swimming-cycling transition (T1), 53.07% for cycling, 0.47% for the cycling-running transition (T2) and 29.5% for running. The correlations between each part of the race and the final placing were: r=0.36 for swimming, r=0.25 for T1, r=0.62 for the cycling, r=0.33 for T2, and r=0.83 for the running. Also, values of r=0.34 & r=0.43 were obtained for Lost Time T1 and Lost Time T2, respectively. In conclusion, losing less time during T2 has been demonstrated to be related to obtaining a better final result.

Intensity control in swim training by means of the individual anaerobic threshold

This study aimed at evaluating the homogeneity of physiological responses during swim training bouts with intensities prescribed by reference to the individual anaerobic threshold (IAT). Eighteen competitive front crawl swimmers (female 5, male 13, 10 long-distance, and 8 short-distance swimmers [LDSs, SDSs], age: 17 ± 1.7 years, training history: 7.0 ± 2.8 years, training volume per week: 35 ± 5.7 km) performed an incremental swimming test to determine the IAT. Within a maximum of 3 weeks, 4 training programs were conducted: 20 × 100-m low-intensity endurance training (EN(low), 97% IAT), 5 × 400-m high-intensity endurance training (EN(high), 101% IAT), 5 × 200 m (IT1, 105% IAT), and 10 × 100 m (IT2, 108% IAT) intensive interval training. Blood lactate concentrations (bLa) were determined during each training session. The results are given as median (25th and 75th percentiles). During EN(low) and EN(high), the mean bLas were 1.8 mmol·L(-1) (1.3/3.0 mmol·L(-1)) and 4.4 mmol·L(-1) (3.9/6.4 mmol·L(-1)). The bLas were higher during both IT programs: IT1, 6.3 mmol·L(-1) (5.6/7.2 mmol·L(-1)); IT2, 5.8 mmol·L(-1) (5.0/6.5 mmol·L(-1)). The bLas of most individuals were close to the median values (±2.4 mmol·L(-1)). However, in each of the training programs, some subjects showed bLa values that were clearly above (3-7 mmol·L(-1) higher). In particular, SDSs reached higher bLas at the same intensity compared with LDSs. It is concluded that intensity prescriptions by means of IAT seem to elicit an expected metabolic response in approximately 85% of swim training sessions. The observed average bLa is in the range of those recommended in the scientific literature.

Guidelines to Classify Subject Groups in Sport-Science Research

Purpose:

The aim of this systematic literature review was to outline the various preexperimental maximal cycle-test protocols, terminology, and performance indicators currently used to classify subject groups in sportscience research and to construct a classification system for cycling-related research.

Methods:

A database of 130 subject-group descriptions contains information on preexperimental maximal cycle-protocol designs, terminology of the subject groups, biometrical and physiological data, cycling experience, and parameters. Kolmogorov-Smirnov test, 1-way ANOVA, post hoc Bonferroni (P < .05), and trend lines were calculated on height, body mass, relative and absolute maximal oxygen consumption (VO2max), and peak power output (PPO).

Results:

During preexperimental testing, an initial workload of 100 W and a workload increase of 25 W are most frequently used. Three-minute stages provide the most reliable and valid measures of endurance performance. After obtaining data on a subject group, researchers apply various terms to define the group. To solve this complexity, the authors introduced the neutral term performance levels 1 to 5, representing untrained, recreationally trained, trained, well-trained, and professional subject groups, respectively. The most cited parameter in literature to define subject groups is relative VO2max, and therefore no overlap between different performance levels may occur for this principal parameter. Another significant cycling parameter is the absolute PPO. The description of additional physiological information and current and past cycling data is advised.

Conclusion:

This review clearly shows the need to standardize the procedure for classifying subject groups. Recommendations are formulated concerning preexperimental testing, terminology, and performance indicators.

The relationship between cadence, pedalling technique and gross efficiency in cycling

Technique and energy saving are two variables often considered as important for performance in cycling and related to each other. Theoretically, excellent pedalling technique should give high gross efficiency (GE). The purpose of the present study was to examine the relationship between pedalling technique and GE. 10 well-trained cyclists were measured for GE, force effectiveness (FE) and dead centre size (DC) at a work rate corresponding to ~75% of VO(2)max during level and inclined cycling, seat adjusted forward and backward, at three different cadences around their own freely chosen cadence (FCC) on an ergometer. Within subjects, FE, DC and GE decreased as cadence increased (p < 0.001). A strong relationship between FE and GE was found, which was to great extent explained by FCC. The relationship between cadence and both FE and GE, within and between subjects, was very similar, irrespective of FCC. There was no difference between level and inclined cycling position. The seat adjustments did not affect FE, DC and GE or the relationship between them. Energy expenditure is strongly coupled to cadence, but force effectiveness, as a measure for pedalling technique, is not likely the cause of this relationship. FE, DC and GE are not affected by body orientation or seat adjustments, indicating that these parameters and the relationship between them are robust to coordinative challenges within a range of cadence, body orientation and seat position that is used in regular cycling.

Influence of road incline and body position on power-cadence relationship in endurance cycling

In race cycling, the external power-cadence relationship at the performance level, that is sustainable for the given race distance, plays a key role. The two variables of interest from this relationship are the maximal external power output (P (max)) and the corresponding optimal cadence (C (opt)). Experimental studies and field observations of cyclists have revealed that when cycling uphill is compared to cycling on level ground, the freely chosen cadence is lower and a more upright body position seems to be advantageous. To date, no study has addressed whether P (max) or C (opt) is influenced by road incline or body position. Thus, the main aim of this study was to examine the effect of road incline (0 vs. 7%) and racing position (upright posture vs. dropped posture) on P (max) and C (opt). Eighteen experienced cyclists participated in this study. Experiment I tested the hypothesis that road incline influenced P (max) and C (opt) at the second ventilatory threshold ([Formula: see text] and [Formula: see text]). Experiment II tested the hypothesis that the racing position influenced [Formula: see text], but not [Formula: see text]. The results of experiment I showed that [Formula: see text] and [Formula: see text] were significantly lower when cycling uphill compared to cycling on level ground (P < 0.01). Experiment II revealed that [Formula: see text] was significantly greater for the upright posture than for the dropped posture (P < 0.01) and that the racing position did not affect [Formula: see text]. The main conclusions of this study were that when cycling uphill, it is reasonable to choose (1) a lower cadence and (2) a more upright body position.

Changes in drive phase lower limb kinematics during a 60 min cycling time trial

OBJECTIVES

The aim of this study was to evaluate changes in the three dimensional lower limb kinematics during a simulated cycling time trial.

DESIGN

Repeated measures.

METHODS

Ten experienced male road cyclists performed a 60 min cycling test at a workload based on previous onset of blood lactate accumulation (OBLA) testing. The time trial (TT) was divided into six 10 min periods consisting of 8 min cycling at steady state (88% of OBLA) followed by a 90 s effort phase (140% of OBLA) and a 30 s recovery phase (60% of OBLA). Three-dimensional kinematic data (200 Hz) were recorded in the last minute of each steady state phase with specific attention directed at changes in range of motion (ROM) and consistency of orientation at the hip, knee and ankle joints during drive phase.

RESULTS

from repeated measures ANOVA indicated a mean effect for test duration on the drive phase ROM in both hip extension (p=0.027) and ankle dorsi flexion (p<0.001). The SD of the mean tibial rotation during the drive phase was the only measure of movement consistency that showed an effect for test duration (p=0.031).

CONCLUSIONS

These findings indicated that participants tended to increase the ROM in hip extension and ankle flexion during drive phase at the end of a TT. Changes in the consistency of tibial rotation during the drive phase may be an important indicator of fatigue and should be monitored by coaches during training due to its possible relationship with injury and fatigue.

Plasma zinc, copper, and serum thyroid hormones and insulin levels after zinc supplementation followed by placebo in competitive athletes

Intense physical activity is associated with biological adaptations involving hormones and trace elements. Zinc supplementation may affect plasma copper concentration, thyroid-stimulating hormone (TSH), thyroid hormones, insulin, and glucose homeostasis, but data in athletes are scarce. The aim of this study was to evaluate in competitive athletes (cyclists, n = 7, 32 ± 8 years) the effect of zinc supplementation (22 mg/day as zinc gluconate) during 30 days, and discontinuation using placebo (maltodextrin) during the following 30 days, on plasma zinc and copper concentrations, serum thyroid hormones, insulin and glucose levels, and HOMA2-IR. Compared to baseline, plasma zinc and Zn:Cu plasma ratio increased, but plasma copper decreased after zinc supplementation (day 30) and discontinuation (day 60) (p < 0.05). Zn supplementation and discontinuation had no effect on TSH, T3, and T4. Fasting serum insulin and HOMA2-IR increased (27% and 47%, respectively) on day 60 compared to baseline (p = 0.03), suggesting a delayed effect of zinc supplementation. Moreover, plasma zinc was positively associated with serum insulin (r = 0.87, p = 0.009) and HOMA2-IR (r = 0.81, p = 0.03) after zinc supplementation (day 30), indicating that supplemental zinc may impair glucose utilization in cyclists.

Exercise ventilatory kinematics in endurance trained and untrained men and women

To determine how increased ventilatory demand impacts ventilatory kinematics, we compared the total chest wall volume variations (V(CW)) of male and female endurance-trained athletes (ET) to untrained individuals (UT) during exercise. We hypothesized that training and gender would have an effect on V(CW) and kinematics at maximal exercise. Gender and training significantly influenced chest wall kinematics. Female ET did not change chest wall end-expiratory volume (V(CW,ee)) or pulmonary ribcage (V(RCp,ee)) with exercise, while female UT significantly decreased V(CW,ee) and V(RCp,ee) with exercise (p<0.05). Female ET significantly increased pulmonary ribcage end-inspiratory volume (V(RCp,ei)) with exercise (p<0.05), while female UT did not change V(RCp,ei) with exercise. Male ET significantly increased V(RCp,ei) with exercise (p<0.05); male UT did not. Men and women had significantly different variation of V(CW) (p<0.05). Women demonstrated the greatest variation of V(CW) in the pulmonary ribcage compartment (V(RCp)). Men had even volumes variation of the V(RCp) and the abdomen (V(Ab)). In conclusion, gender and training had a significant impact on ventilatory kinematics.

Power-cadence relationship in endurance cycling

In maximal sprint cycling, the power-cadence relationship to assess the maximal power output (P (max)) and the corresponding optimal cadence (C (opt)) has been widely investigated in experimental studies. These studies have generally reported a quadratic power-cadence relationship passing through the origin. The aim of the present study was to evaluate an equivalent method to assess P (max) and C (opt) for endurance cycling. The two main hypotheses were: (1) in the range of cadences normally used by cyclists, the power-cadence relationship can be well fitted with a quadratic regression constrained to pass through the origin; (2) P (max) and C (opt) can be well estimated using this quadratic fit. We tested our hypothesis using a theoretical and an experimental approach. The power-cadence relationship simulated with the theoretical model was well fitted with a quadratic regression and the bias of the estimated P (max) and C (opt) was negligible (1.0 W and 0.6 rpm). In the experimental part, eight cyclists performed an incremental cycling test at 70, 80, 90, 100, and 110 rpm to yield power-cadence relationships at fixed blood lactate concentrations of 3, 3.5, and 4 mmol L(-1). The determined power outputs were well fitted with quadratic regressions (R (2) = 0.94-0.96, residual standard deviation = 1.7%). The 95% confidence interval for assessing individual P (max) and C (opt) was ±4.4 W and ±2.9 rpm. These theoretical and experimental results suggest that P (max), C (opt), and the power-cadence relationship around C (opt) could be well estimated with the proposed method.

Aspectos relacionados com a otimização do treinamento aeróbio para o alto rendimento

O objetivo deste trabalho foi apresentar recomendações visando à otimização do treinamento aeróbio, a partir do conhecimento dos índices de aptidão funcional e seus mecanismos fisiológicos. Em atletas altamente treinados, a precisão na elaboração do treinamento pode ser o meio mais seguro para a melhora do rendimento, pois nesses indivíduos é comum a carga de treinamento oscilar entre o estimulo insuficiente e o aparecimento do excesso de treinamento. Existe, portanto, uma variedade muito grande de fatores que devem ser considerados na elaboração de um programa de treinamento. O entendimento dos mecanismos de fadiga e das respostas fisiológicas associadas às diferentes durações e intensidades de exercício é essencial para uma correta elaboração das sessões de treinamento. Além disso, treinos intervalados de alta intensidade são imprescindíveis para melhora de rendimento em atletas altamente treinados, porém, é recomendado que ele seja realizado após um razoável período de recuperação das sessões de treino anteriores. Assim, o contato entre o atleta e o treinador é importante para um planejamento cuidadoso dos períodos de recuperação antes da ocorrência de fadiga excessiva. O treinador deveria arquivar um histórico das cargas de treino e recuperações, aprendendo com a própria experiência os tipos de cargas que podem ser toleradas individualmente. Entre os fatores que podem afetar o rendimento aeróbio, o planejamento de um aquecimento apropriado e as condições ambientais adversas são aspectos muito importantes. Após reunir todas essas informações, é possível elaborar as bases do treinamento (frequência, volume, intensidade e recuperação) visando melhora contínua do rendimento aeróbio.

Effects of two neuromuscular fatigue protocols on landing performance

The purpose of the study was to investigate the effects of two fatigue protocols on landing performance. A repeated measures design was used to examine the effects of fatigue and fatigue protocol on neuromuscular and biomechanical performance variables. Ten volunteers performed non-fatigued and fatigued landings on two days using different fatigue protocols. Repeated maximum isometric squats were used to induce fatigue on day one. Sub-maximum cycling was used to induce fatigue on day two. Isometric squat maximum voluntary contraction (MVC) was measured before and after fatigued landings on each day. During the landings, ground reaction force (GRF), knee kinematics, and electromyographic (EMG) data were recorded. Isometric MVC, GRF peaks, loading rates, impulse, knee flexion at contact, range of motion, max angular velocity, and EMG root mean square (RMS) values were compared pre- and post-fatiguing exercise and between fatigue protocols using repeated ANOVA. Fatigue decreased MVC strength (p0.05), GRF second peak, and initial impulse (p0.01), but increased quadriceps medium latency stretch reflex EMG activity (p0.012). Knee flexion at contact was 5.2 degrees greater (p0.05) during fatigued landings following the squat exercise compared to cycling. Several variables exhibited non-significant but large effect sizes when comparing the effects of fatigue and fatigue protocol. In conclusion, fatigue alters landing performance and different fatigue protocols result in different performance changes.

Evaluation and opportunities in overtraining approaches

Overtraining (OT) as a sports phenomenon can be caused by stressors on various levels (physical, emotional, psychological, and social) and evokes responses on these levels. This study evaluated research and new opportunities in the field of OT by introducing an integrated multidisciplinary approach, based on the single and multistressors approach. The single stressor approach focuses on the training load-recovery imbalance, which results in a stagnating performance, excluding the etiology by nonsport-related factors. The multistressors approach includes all factors as relevant in the etiology of a stagnating performance. In future studies on OT an integrative approach should not only highlight changes in training regimes and specific responses to training stressors but also focus on the role of training-related recovery, the impact of stressors, and personality factors influencing stress appraisal. This will provide a better insight into the etiology and consequences of OT necessary for prevention and treatment in sport practice, and enhance the focus on adequate recovery (good sleep, sufficient rest periods) and athletes' stress-related responses.

Training in hypoxia fails to further enhance endurance performance and lactate clearance in well-trained men and impairs glucose metabolism during prolonged exercise

The aim of this study was to investigate the synergistic effects of endurance training and hypoxia on endurance performance in normoxic and hypoxic conditions (approximately 3000 m above sea level) as well as on lactate and glucose metabolism during prolonged exercise. For this purpose, 14 well-trained cyclists performed 12 training sessions in conditions of normobaric hypoxia (HYP group, n = 7) or normoxia (NOR group, n = 7) over 4 weeks. Before and after training, lactate and glucose turnover rates were measured by infusion of exogenous lactate and stable isotope tracers. Endurance performance was assessed during incremental tests performed in normoxia and hypoxia and a 40 km time trial performed in normoxia. After training, performance was similarly and significantly improved in the NOR and HYP groups (training, P < 0.001) in normoxic conditions. No further effect of hypoxic training was found on markers of endurance performance in hypoxia (training x hypoxia interaction, n.s.). In addition, training and hypoxia had no significant effect on lactate turnover rate. In contrast, there was a significant interaction of training and hypoxia (P < 0.05) on glucose metabolism, as follows: plasma insulin and glucose concentrations were significantly increased; glucose metabolic clearance rate was decreased; and the insulin to glucagon ratio was increased after training in the HYP group. In conclusion, our results show that, compared with training in normoxia, training in hypoxia has no further effect on endurance performance in both normoxic and hypoxic conditions or on lactate metabolic clearance rate. Additionally, these findings suggest that training in hypoxia impairs blood glucose regulation in endurance-trained subjects during exercise.

Tuning of mitochondrial pathways by muscle work: from triggers to sensors and expression signatures

Performance of striated muscle relies on the nerve-driven activation of the sarcomeric motor and coupled energy supply lines. This biological engine is unique; its mechanical and metabolic characteristics are not fixed, but are tailored by functional demand with exercise. This remodelling is specific for the imposed muscle stimulus. This is illustrated by the increase in local oxidative capacity with highly repetitive endurance training vs. the preferential initiation of sarcomerogenesis with strength training regimes, where high-loading increments are imposed. The application of molecular biology has provided unprecedented insight into the pathways that govern muscle plasticity. Time-course analysis indicates that the adjustments to muscle work involve a broad regulation of transcript expression during the recovery phase from a single bout of exercise. Highly resolving microarray analysis demonstrates that the specificity of an endurance-exercise stimulus is reflected by the signature of the transcriptome response after muscle work. A quantitative match in mitochondrial transcript adjustments and mitochondrial volume density after endurance training suggests that the gradual accumulation of expressional microadaptations underlies the promotion of fatigue resistance with training. This regulation is distinguished from control of muscle growth via the load-dependent activation of sarcomerogenesis. Discrete biochemical signalling systems have evolved that sense metabolic perturbations during exercise and trigger a specific expression program, which instructs the remodelling of muscle makeup. A drop in muscle oxygen tension and metabolite perturbations with exercise are recognized as important signals in the genome-mediated remodelling of the metabolic muscle phenotype in humans.

Prediction of maximal oxygen uptake from submaximal ratings of perceived exertion and heart rate during a continuous exercise test: the efficacy of RPE 13

This study assessed the utility of a single, continuous exercise protocol in facilitating accurate estimates of maximal oxygen uptake V(O)(2max) from submaximal heart rate (HR) and the ratings of perceived exertion (RPE) in healthy, low-fit women, during cycle ergometry. Eleven women estimated their RPE during a continuous test (1 W 4 s(-1)) to volitional exhaustion (measured V(O)(2max)). Individual gaseous exchange thresholds (GETs) were determined retrospectively. The RPE and HR values prior to and including an RPE 13 and GET were extrapolated against corresponding oxygen uptake to a theoretical maximal RPE (20) and peak RPE (19), and age-predicted HRmax, respectively, to predict V(O)(2max)). There were no significant differences (P > 0.05) between measured (30.9 +/- 6.5 ml kg(-1) min(-1)) and predicted V(O)(2max) from all six methods. Limits of agreement were narrowest and intraclass correlations were highest for predictions of V(O)(2max) from an RPE 13 to peak RPE (19). Prediction of V(O)(2max) from a regression equation using submaximal HR and work rate at an RPE 13 was also not significantly different to actual V(O)(2max) (R( 2 ) = 0.78, SEE = 3.42 ml kg(-1) min(-1), P > 0.05). Accurate predictions of V(O)(2max) may be obtained from a single, continuous, estimation exercise test to a moderate intensity (RPE 13) in low-fit women, particularly when extrapolated to peak terminal RPE (RPE(19)). The RPE is a valuable tool that can be easily employed as an adjunct to HR, and provides supplementary clinical information that is superior to using HR alone.

Influence of crank length and crank width on maximal hand cycling power and cadence

The effect of different crank lengths and crank widths on maximal hand cycling power, cadence and handle speed were determined. Crank lengths and crank widths were adapted to anthropometric data of the participants as the ratio to forward reach (FR) and shoulder breadth (SB), respectively. 25 able-bodied subjects performed maximal inertial load hand cycle ergometry using crank lengths of 19, 22.5 and 26% of FR and 72, 85 and 98% of SB. Maximum power ranged from 754 (246) W for the crank geometry short wide (crank length x crank width) to 873 (293) W for the combination long middle. Every crank length differed significantly (P < 0.05) from each other, whereas no significant effect of crank width to maximum power output was revealed. Optimal cadence decreased significantly (P < 0.001) with increasing crank length from 124.8 (0.9) rpm for the short to 107.5 (1.6) rpm for the long cranks, whereas optimal handle speed increased significantly (P < 0.001) with increasing crank length from 1.81 (0.01) m/s for the short to 2.13 (0.03) m/s for the long cranks. Crank width did neither influence optimal cadence nor optimal handle speed significantly. From the results of this study, for maximum hand cycling power, a crank length to FR ratio of 26% for a crank width to SB ratio of 85% is recommended.

Which factors determine the freely chosen cadence during submaximal cycling?

The present review of cycling science focuses on the identification of criteria that affect the freely chosen cadence (FCC) during submaximal exercise of short and prolonged durations. Cadence selection during submaximal cycling constitutes a potential parameter affecting the endurance performance in subjects of varying aerobic fitness level and experience. The activity constraints such as specificity (e.g. cycle bout of triathlon) and exercise duration may play an important role in the selection of cadence and must be taken into consideration in the task description. The 'holistic' approach of this review is based on a multifactorial analysis considering the cycling constraints, and the physiological and biomechanical factors of cadence selection so as to establish any interrelationships between these factors. During cycle bouts of short duration (<15 min), it has been well argued that experienced cyclists, trained runners and triathletes adopt high cadences (80-100 rpm) systematically above the energetically optimal cadence (EOC) at which the oxygen uptake is minimal (55-65 rpm). The choice of a high cadence has been shown to be dependent upon several factors, such as the aerobic fitness level, the reduction in forces applied to the cranks, the lower extremity net joint moments and minimal neuromuscular fatigue. However, with increasing exercise duration the FCC has been reported to be close to the EOC exclusively in endurance athletes practising a variety of activities, suggesting an impact of training mode on the muscular adaptations and the organisation of the movement pattern.

The rotor pedaling system improves anaerobic but not aerobic cycling performance in professional cyclists

The aims of this study were to evaluate the effects of both noncircular (ROT) and conventional (CON) chainring systems on aerobic and anaerobic cycling performances of professional cyclists, while analyzing the influence of varying the crank angle of maximum crank arm length of ROT. Fifteen professional road cyclists performed both incremental and sub-maximal aerobic tests and the Wingate anaerobic test in the laboratory. There were no statistical differences between CON and ROT in the aerobic tests, even when the best ROT position (ROT+) was selected. However, in the anaerobic test, maximal (4.2-9.1%) and mean (0.7-4.7%) power outputs were higher in ROT (P < 0.05). These differences were greater when the ROT+ was selected (11.2 and 7.0%, respectively). Our findings suggest that ROT is able to improve anaerobic but not aerobic cycling performance in professional cyclists. Nevertheless, it must be adapted to each cyclist to ensure these improvements.

Seasonal changes in aerobic fitness indices in elite cyclists

The primary purpose of this study was to compare seasonal changes in cycling gross efficiency (GE) and economy (EC) with changes in other aerobic fitness indices. The secondary aim was to assess the relationship between maximum oxygen consumption, GE, and EC among elite cyclists. The relationships of maximum oxygen consumption with GE and EC were studied in 13 cyclists (8 professional road cyclists and 5 mountain bikers). Seasonal changes in GE and EC, predicted time to exhaustion (pTE), maximum oxygen consumption, and respiratory compensation point (RCP) were examined in a subgroup of 8 subjects, before (TREST) and after (TPRECOMP) the pre-competitive winter training, and during the competitive period (TCOMP). GE and EC were assessed during a constant power test at 75% of peak power output (PPO). Significant main effect for time was found for maximum oxygen consumption (4.623 +/- 0.675, 4.879 +/- 0.727, and 5.010 +/- 0.663 L.min(-1); p = 0.028), PPO (417.8 +/- 46.5, 443.0 +/- 48.0, and 455 +/- 48 W; p < 0.001), oxygen uptake at RCP (3.866 +/- 0.793, 4.041 +/- 0.685, and 4.143 +/- 0.643 L.min(-1); p = 0.049), power output at RCP (330 +/- 64, 354 +/- 52, and 361 +/- 50 W; p < 0.001), and pTE (17 +/- 4, 30 +/- 8, and 46 +/- 17 min; p < 0.001). No significant main effect for time was found in GE (p = 0.097) or EC (p = 0.225), despite within-subject seasonal changes. No significant correlations were found between absolute maximum oxygen consumption and GE (r = -0.276; p = 0.359) or EC (r = -0.328; p = 0.272). However, cyclists with high maximum oxygen consumption values (i.e., over 80 mL.kg(-1).min(-1)), showed low efficiency rates. Despite within-subject seasonal waves in cycling efficiency, changes in GE and EC should not be expected as direct consequence of changes in other maximal and submaximal parameters of aerobic fitness (i.e., maximum oxygen consumption and RCP).

Effect of age on 16.1-km time-trial performance

In this study, we assessed the performance of trained senior (n = 6) and veteran (n = 6) cyclists (mean age 28 years, s = 3 and 57 years, s = 4 respectively). Each competitor completed two cycling tests, a ramped peak aerobic test and an indoor 16.1-km time-trial. The tests were performed using a Kingcycle ergometer with the cyclists riding their own bicycle fitted with an SRM powermeter. Power output, heart rate, and gas exchange variables were recorded continuously and blood lactate concentration [HLa] was assessed 3 min after the peak ramped test and at 2.5-min intervals during the time-trial. Peak values for power output (RMP(max)), heart rate (HR(peak)), oxygen uptake (VO2(peak)), and ventilation (V(Epeak)) attained during the ramped test were higher in the senior group (P < 0.05), whereas [HLa](peak), RER(peak), V(E): VO2(peak), and economy(peak) were similar between groups (P > 0.05). Time-trial values (mean for duration of race) for power output (W(TT)), heart rate (HR(TT)), VO2 (VO(2TT)), and V(E) (V(ETT)) were higher in the seniors (P < 0.05), but [HLa](TT), RER(TT), V(ETT): VO2(TT), and economy(TT) were similar between the groups (P > 0.05). Time-trial exercise intensity, expressed as %RMP(max), %HR(peak), % VO2(peak), and % V(Epeak), was similar (P > 0.05) for seniors and veterans (W(TT): 81%, s = 2 vs. 78%, s = 8; HR(TT): 96%, s = 4 vs. 94%, s = 4; VO2(TT): 92%, s = 4 vs. 95%, s = 10; V(ETT): 89%, s = 8 vs. 85%, s = 8, respectively). Overall, seniors attained higher absolute values for power output, heart rate, VO2, and V(E) but not blood lactate concentration, respiratory exchange ratio (RER), V(E): VO2, and economy. Veterans did not accommodate age-related declines in time trial performance by maintaining higher relative exercise intensity.

Training to enhance the physiological determinants of long-distance running performance: can valid recommendations be given to runners and coaches based on current scientific knowledge?

This article investigates whether there is currently sufficient scientific knowledge for scientists to be able to give valid training recommendations to long-distance runners and their coaches on how to most effectively enhance the maximal oxygen uptake, lactate threshold and running economy. Relatively few training studies involving trained distance runners have been conducted, and these studies have often included methodological factors that make interpretation of the findings difficult. For example, the basis of most of the studies was to include one or more specific bouts of training in addition to the runners' 'normal training', which was typically not described or only briefly described. The training status of the runners (e.g. off-season) during the study period was also typically not described. This inability to compare the runners' training before and during the training intervention period is probably the main factor that hinders the interpretation of previous training studies. Arguably, the second greatest limitation is that only a few of the studies included more than one experimental group. Consequently, there is no comparison to allow the evaluation of the relative efficacy of the particular training intervention. Other factors include not controlling the runners' training load during the study period, and employing small sample sizes that result in low statistical power. Much of the current knowledge relating to chronic adaptive responses to physical training has come from studies using sedentary individuals; however, directly applying this knowledge to formulate training recommendations for runners is unlikely to be valid. Therefore, it would be difficult to argue against the view that there is insufficient direct scientific evidence to formulate training recommendations based on the limited research. Although direct scientific evidence is limited, we believe that scientists can still formulate worthwhile training recommendations by integrating the information derived from training studies with other scientific knowledge. This knowledge includes the acute physiological responses in the various exercise domains, the structures and processes that limit the physiological determinants of long-distance running performance, and the adaptations associated with their enhancement. In the future, molecular biology may make an increasing contribution in identifying effective training methods, by identifying the genes that contribute to the variation in maximal oxygen uptake, the lactate threshold and running economy, as well as the biochemical and mechanical signals that induce these genes. Scientists should be cautious when giving training recommendations to runners and coaches based on the limited available scientific knowledge. This limited knowledge highlights that characterising the most effective training methods for long-distance runners is still a fruitful area for future research.

Electromyographic analysis of pedaling: a review

Although pedaling is constrained by the circular trajectory of the pedals, it is not a simple movement. This review attempts to provide an overview of the pedaling technique using an electromyographic (EMG) approach. Literature concerning the electromyographic analysis of pedaling is reviewed in an effort to make a synthesis of the available information, and to point out its relevance for researchers, clinicians and/or cycling/triathlon trainers. The first part of the review depicts methodological aspects of the EMG signal recording and processing. We show how the pattern of muscle activation during pedaling can be analyzed in terms of muscle activity level and muscle activation timing. Muscle activity level is generally quantified with root mean square or integrated EMG values. Muscle activation timing is studied by defining EMG signal onset and offset times that identify the duration of EMG bursts and, more recently, by the determination of a lag time maximizing the cross-correlation coefficient. In the second part of the review, we describe whether the patterns of the lower limb muscles activity are influenced by numerous factors affecting pedaling such as power output, pedaling rate, body position, shoe-pedal interface, training status and fatigue. Some research perspectives linked to pedaling performance are discussed throughout the manuscript and in the conclusion.

Case Report on PWC of a Competitive Cyclist before and after Heart Transplant

INTRODUCTION

It has been well documented that for heart transplant recipients (HTR), posttransplantation physical work capacity (PWC) normally does not exceed 60% of the value for healthy age-matched controls. Few, if any, studies have undertaken posttransplantation PWC measurements of well-conditioned individuals (i.e., PWC>300 W).

CASE SUMMARY

A 37-yr-old professionally trained male cyclist suffered an acute myocardial infarction (AMI) immediately after a road race and received a heart transplant (HT) 4 months after the AMI. The participant resumed training 1 month after surgery and underwent a maximal exercise test 6 months after surgery. Peak PWC (33.8 mL.kg(-1).min(-1), 250 W) was 92% of the age-predicted maximum, and peak heart rate (165 bpm) was 96% of his known maximum. These results were similar to the participants in a study who had been training regularly for 36+/-24 months before testing, and PWC evaluations occurred 43+/-12 months after HT.

CONCLUSION

Results suggest that 1) lifestyle before HT may positively affect posttransplantation PWC, 2) exercise capacity was not limited by chronotropic incompetence, and 3) a more aggressive approach to HT recovery could be applied to HTR with similar activity histories.

The interactive effect of exercise intensity and task difficulty on human cognitive processing

The interactive effect of exercise intensity and task difficulty on human cognitive processing was investigated using the P3 component of an event-related brain potential (ERP). Exercise intensity was established using Borg's rating of perceived exertion (RPE) scale, and task difficulty was manipulated using a modified flanker task comprised of incongruent and neutral trials. Twelve participants (22 to 30 y) performed the flanker task during a baseline session, and again after light (RPE: 11), moderate (RPE: 13), and hard (RPE: 15) cycling exercise. Results indicated that the P3 amplitude increases across task conditions following light and moderate cycling, but not during hard cycling, relative to baseline, suggesting that P3 amplitude may change in an inverted U fashion by as a result of acute exercise intensity. Additionally, the expected delay in P3 latency for incongruent relative to neutral trials was observed during the baseline condition. However, following acute exercise these task condition differences diminished across exercise intensities. Moreover, reaction times following all exercise conditions were shorter when compared to the baseline condition. These findings suggest that P3 latency is more sensitive to task difficulty manipulated by a flanker task than behavioral measures, and P3 latency during trials requiring greater executive control processes might be more sensitive to the effects of acute exercise than tasks requiring minimal effort.

Incremental Exercise Test Design and Analysis

Physiological variables, such as maximum work rate or maximal oxygen uptake (VO2max), together with other submaximal metabolic inflection points (e.g. the lactate threshold [LT], the onset of blood lactate accumulation and the pulmonary ventilation threshold [VT]), are regularly quantified by sports scientists during an incremental exercise test to exhaustion. These variables have been shown to correlate with endurance performance, have been used to prescribe exercise training loads and are useful to monitor adaptation to training. However, an incremental exercise test can be modified in terms of starting and subsequent work rates, increments and duration of each stage. At the same time, the analysis of the blood lactate/ventilatory response to incremental exercise may vary due to the medium of blood analysed and the treatment (or mathematical modelling) of data following the test to model the metabolic inflection points. Modification of the stage duration during an incremental exercise test may influence the submaximal and maximal physiological variables. In particular, the peak power output is reduced in incremental exercise tests that have stages of longer duration. Furthermore, the VT or LT may also occur at higher absolute exercise work rate in incremental tests comprising shorter stages. These effects may influence the relationship of the variables to endurance performance or potentially influence the sensitivity of these results to endurance training. A difference in maximum work rate with modification of incremental exercise test design may change the validity of using these results for predicting performance, and prescribing or monitoring training. Sports scientists and coaches should consider these factors when conducting incremental exercise testing for the purposes of performance diagnostics.

The ecological validity of laboratory cycling: Does body size explain the difference between laboratory- and field-based cycling performance?

Previous researchers have identified significant differences between laboratory and road cycling performances. To establish the ecological validity of laboratory time-trial cycling performances, the causes of such differences should be understood. Hence, the purpose of the present study was to quantify differences between laboratory- and road-based time-trial cycling and to establish to what extent body size [mass (m) and height (h)] may help to explain such differences. Twenty-three male competitive, but non-elite, cyclists completed two 25 mile time-trials, one in the laboratory using an air-braked ergometer (Kingcycle) and the other outdoors on a local road course over relatively flat terrain. Although laboratory speed was a reasonably strong predictor of road speed (R2 = 69.3%), a significant 4% difference (P < 0.001) in cycling speed was identified (laboratory vs. road speed: 40.4 +/- 3.02 vs. 38.7 +/- 3.55 km x h(-1); mean +/- s). When linear regression was used to predict these differences (Diff) in cycling speeds, the following equation was obtained: Diff (km x h(-1)) = 24.9 - 0.0969 x m - 10.7 x h, R2 = 52.1% and the standard deviation of residuals about the fitted regression line = 1.428 (km . h-1). The difference between road and laboratory cycling speeds (km x h(-1)) was found to be minimal for small individuals (mass = 65 kg and height = 1.738 m) but larger riders would appear to benefit from the fixed resistance in the laboratory compared with the progressively increasing drag due to increased body size that would be experienced in the field. This difference was found to be proportional to the cyclists' body surface area that we speculate might be associated with the cyclists' frontal surface area.