Robert P. Lamberts

Exercising with reserve: exercise regulation by perceived exertion in relation to duration of exercise and knowledge of endpoint

Objective: The purpose of this study was to examine ratings of perceived exertion (RPE) and performance during repetitive maximal effort 40 km time trials as well as after an intervention that aimed to decrease certainty about the remaining distance of the exercise bout. In addition, we examined the RPE during exercise bouts of markedly different duration. Methods: Part 1: 12 well-trained, competitive-level cyclists completed five 40 km time trials. During the final time trial all feedback was withheld until the final kilometre. In addition, to cause confusion about the remaining distance, they were asked to report their RPE at random intervals from 18 km to 38 km. Part 2: 6 well-trained, recreation-level cyclists randomly completed a 5 km, 10 km, 40 km and 100 km time trial. Results: Part 1: Mean RPE increased during the first four trials and decreased during the final trial. The rate of RPE progression increased in linearity during the first four trials and became more conservative in the final trial. These changes were directly related to performance. Part 2: Mean RPE for longer duration trials (40 km, 100 km) were lower during the first half of trial duration but matched those of shorter trials in the final 20%. Conclusions: Increased familiarity of the exercise bout and certainty about its endpoint are associated with a more aggressive RPE strategy that produces a superior exercise performance. Certainty about the endpoint and the duration of exercise affect both the RPE strategy and performance.

Exercising with reserve: evidence that the central nervous system regulates prolonged exercise performance

Objective: The purpose of this study was to measure the effects of an amphetamine (methylphenidate) on exercise performance at a fixed rating of perceived exertion of 16. Methods: Eight elite cyclists ingested 10 mg methylphenidate in a randomised, placebo-controlled crossover trial. Results: Compared with placebo, subjects receiving methylphenidate cycled for approximately 32% longer before power output fell to 70% of the starting value. At the equivalent time at which the placebo trial terminated, subjects receiving methylphenidate had significantly higher power outputs, oxygen consumptions, heart rates, ventilatory volumes and blood lactate concentrations although electromyographic activity remained unchanged. The ingestion of a centrally acting stimulant thus allowed subjects to exercise for longer at higher cardiorespiratory and metabolic stress indicating the presence of a muscular reserve in the natural state. Conclusions: This suggests that endurance performance is not only “limited” by mechanical failure of the exercising muscles (“peripheral fatigue”). Rather performance during prolonged endurance exercise under normal conditions is highly regulated by the central nervous system to ensure that whole-body homeostasis is protected and an emergency reserve is always present.

Heart rate recovery as a guide to monitor fatigue and predict changes in performance parameters.

Determining the optimal balance between training load and recovery contributes to peak performance in well‐trained athletes. The measurement of heart rate recovery (HRR) to monitor this balance has become popular. However, it is not known whether the impairment in performance, which is associated with training‐induced fatigue, is accompanied by a change in HRR. Therefore, the aim of this study was to retrospectively analyze the relationship between changes in HRR and cycling performance in a group of well‐trained cyclists (n=14) who participated in a 4‐week high‐intensity training (HIT) program. Subjects were assigned to either a group that continuous had a increase in HRR (GIncr) or a group that showed a decrease in HRR (GDecr) during the HIT period. Both groups, GIncr and GDecr, showed improvements in the relative peak power output (P=0.001 and 0.016, respectively) and endurance performance parameters (P=0.001 and <0.048, respectively). The average power during the 40‐km time trial (40‐km TT), however, improved more in GIncr (P=0.010), resulting in a tendency for a faster 40‐km TT time (P=0.059). These findings suggest that HRR has the potential to monitor changes in endurance performance and contribute to a more accurate prescription of training load in well‐trained and elite cyclists.

Methods of Prescribing Relative Exercise Intensity: Physiological and Practical Considerations

Exercise prescribed according to relative intensity is a routine feature in the exercise science literature and is intended to produce an approximately equivalent exercise stress in individuals with different absolute exercise capacities. The traditional approach has been to prescribe exercise intensity as a percentage of maximal oxygen uptake (VO2max) or maximum heart rate (HRmax) and these methods remain common in the literature. However, exercise intensity prescribed at a %VO2max or %HRmax does not necessarily place individuals at an equivalent intensity above resting levels. Furthermore, some individuals may be above and others below metabolic thresholds such as the aerobic threshold (AerT) or anaerobic threshold (AnT) at the same %VO2max or %HRmax. For these reasons, some authors have recommended that exercise intensity be prescribed relative to oxygen consumption reserve (VO2R), heart rate reserve (HRR), the AerT, or the AnT rather than relative to VO2max or HRmax. The aim of this review was to compare the physiological and practical implications of using each of these methods of relative exercise intensity prescription for research trials or training sessions. It is well established that an exercise bout at a fixed %VO2max or %HRmax may produce interindividual variation in blood lactate accumulation and a similar effect has been shown when relating exercise intensity to VO2R or HRR. Although individual variation in other markers of metabolic stress have seldom been reported, it is assumed that these responses would be similarly heterogeneous at a %VO2max, %HRmax, %VO2R, or %HRR of moderate-to-high intensity. In contrast, exercise prescribed relative to the AerT or AnT would be expected to produce less individual variation in metabolic responses and less individual variation in time to exhaustion at a constant exercise intensity. Furthermore, it would be expected that training prescribed relative to the AerT or AnT would provide a more homogenous training stimulus than training prescribed as a %VO2max. However, many of these theoretical advantages of threshold-related exercise prescription have yet to be directly demonstrated. On a practical level, the use of threshold-related exercise prescription has distinct disadvantages compared to the use of %VO2max or %HRmax. Thresholds determined from single incremental tests cannot be assumed to be accurate in all individuals without verification trials. Verification trials would involve two or three additional laboratory visits and would add considerably to the testing burden on both the participant and researcher. Threshold determination and verification would also involve blood lactate sampling, which is aversive to some participants and has a number of intrinsic and extrinsic sources of variation. Threshold measurements also tend to show higher day-to-day variation than VO2max or HRmax. In summary, each method of prescribing relative exercise intensity has both advantages and disadvantages when both theoretical and practical considerations are taken into account. It follows that the most appropriate method of relative exercise intensity prescription may vary with factors such as exercise intensity, number of participants, and participant characteristics. Considering a method’s limitations as well as advantages and increased reporting of individual exercise responses will facilitate accurate interpretation of findings and help to identify areas for further study.

High Responders and Low Responders: Factors Associated with Individual Variation in Response to Standardized Training

The response to an exercise intervention is often described in general terms, with the assumption that the group average represents a typical response for most individuals. In reality, however, it is more common for individuals to show a wide range of responses to an intervention rather than a similar response. This phenomenon of ‘high responders’ and ‘low responders’ following a standardized training intervention may provide helpful insights into mechanisms of training adaptation and methods of training prescription. Therefore, the aim of this review was to discuss factors associated with inter-individual variation in response to standardized, endurance-type training. It is well-known that genetic influences make an important contribution to individual variation in certain training responses. The association between genotype and training response has often been supported using heritability estimates; however, recent studies have been able to link variation in some training responses to specific single nucleotide polymorphisms. It would appear that hereditary influences are often expressed through hereditary influences on the pre-training phenotype, with some parameters showing a hereditary influence in the pre-training phenotype but not in the subsequent training response. In most cases, the pre-training phenotype appears to predict only a small amount of variation in the subsequent training response of that phenotype. However, the relationship between pre-training autonomic activity and subsequent maximal oxygen uptake response appears to show relatively stronger predictive potential. Individual variation in response to standardized training that cannot be explained by genetic influences may be related to the characteristics of the training program or lifestyle factors. Although standardized programs usually involve training prescribed by relative intensity and duration, some methods of relative exercise intensity prescription may be more successful in creating an equivalent homeostatic stress between individuals than other methods. Individual variation in the homeostatic stress associated with each training session would result in individuals experiencing a different exercise ‘stimulus’ and contribute to individual variation in the adaptive responses incurred over the course of the training program. Furthermore, recovery between the sessions of a standardized training program may vary amongst individuals due to factors such as training status, sleep, psychological stress, and habitual physical activity. If there is an imbalance between overall stress and recovery, some individuals may develop fatigue and even maladaptation, contributing to variation in pre–post training responses. There is some evidence that training response can be modulated by the timing and composition of dietary intake, and hence nutritional factors could also potentially contribute to individual variation in training responses. Finally, a certain amount of individual variation in responses may also be attributed to measurement error, a factor that should be accounted for wherever possible in future studies. In conclusion, there are several factors that could contribute to individual variation in response to standardized training. However, more studies are required to help clarify and quantify the role of these factors. Future studies addressing such topics may aid in the early prediction of high or low training responses and provide further insight into the mechanisms of training adaptation.

Variation in heart rate during submaximal exercise: Implications for monitoring training

&NA; Lamberts, R.P., K.A.P.M. Lemmink, J.J. Durandt, and M.I. Lambert. Variation in heart rate during submaximal exercise: implications for monitoring training. J. Strength Cond. Res. 18(3):641–645. 2004.—A change in heart rate at a controlled submaximal exercise intensity is used as a marker of training status. However, the standard error of measurement has not been studied systematically, and therefore a change in heart rate, which can be considered relevant, has not been determined. Forty‐four subjects (26.5 ± 5.4 years; mean ± standard deviation) participated in a submaximal running test at the same time of day for 5 consecutive days. Heart rates were determined during each of the 4 exercise intensities (2 minutes each) of increasing intensity and during the 1‐minute recovery period after each stage. The repeatability of the heart rate on a day‐to‐day basis during the stages and recovery periods were high (intraclass correlation coefficient: 95% confidence interval R = 0.94–0.99). The lowest variation in heart rate occurred in the fourth stage (≈90% maximum heart rate) with heart rate varying 5 ± 2 b·min‐1 (95% confidence interval for coefficient of variation = 1.1–1.4%). In conclusion, the standard error of measurement of submaximal heart rate is 1.1–1.4%. This magnitude of measurement error needs to be considered when heart rate is used as a marker of training status.

Day-to-day variation in heart rate at different levels of submaximal exertion: implications for monitoring training.

Lamberts, RP and Lambert, MI. Day-to-day variation in heart rate at different levels of submaximal exertion: implications for monitoring training. J Strength Cond Res 23(3): 1005-1010, 2009-The HIMS test, which consists of controlled exercise at increasing workloads, has been developed to monitor changes in training status and accumulative fatigue in athletes. As the workload can influence the day-to-day variation in heart rate, the exercise intensity, which is associated with the highest sensitivity, needs to be established with the goal of refining the interpretability of these heart rate measurements. The aim of the study was to determine the within-subject day-to-day variation of submaximal and recovery heart rate in subjects who reached different exercise intensities. Thirty-eight subjects participated in this study and after familiarization were allocated to 1 of 4 groups based on the percentage of predicted heart rate maximum that was elicited during the first test (i.e., groups: <85, 85-90, 90-95, and >95% maximum heart rate). Variation in heart rate was determined for the following 4 days at a range of intensities (61-98% of maximum heart rate) and recovery periods. Variation in heart rate decreased with increasing exercise intensity in all groups. The lowest variation in heart rate was found at the end of the last stage of the test in the 85-90% group (3 ± 1 b·min−1) and >95% group (3 ± 2 b·min−1). The lowest variation during the recovery periods occurred at the first minute after the last stage. Although there were no significant differences between the groups, the 85-90% group showed a tendency to have the lowest variation in heart rate. If changes in heart rate and heart rate recovery are to be monitored in athletes, a submaximal protocol should elicit heart rate between 85 and 90% of maximum heart rate, because this intensity is associated with the least day-to-day variation.

A novel submaximal cycle test to monitor fatigue and predict cycling performance.

Objective The purpose of this study was to determine the reliability and predictive value of performance parameters, measured by a new novel submaximal cycle protocol, on peak power and endurance cycling performance in well-trained cyclists. Methods Seventeen well-trained competitive male road racing cyclists completed four peak power output (PPO) tests and four 40-km time trials (40-km TT). Before each test, all cyclists performed a novel submaximal cycle test (Lamberts and Lambert Submaximal Cycle Test (LSCT)). Parameters associated with performance such as power, speed, cadence and rating of perceived exertion (RPE) were measured during the three stages of the test when cyclists rode at workloads coinciding with fixed predetermined heart rates. Heart rate recovery (HRR) was measured after the last stage of the test. Results Parameters measured during the second and third stages of the LSCT were highly reliable (intraclass correlation range: R=0.85−1.00) with low typical error of measurements (range: 1.3−4.4%). Good relationships were found between the LSCT and cycling performance measured by the PPO and 40-km TT tests. Mean power had stronger relationships with measures of cycling performance during the second (r=0.80−0.89) and third stages (r=0.91−0.94) of the LSCT than HRR (r=0.55−0.68). Conclusions The LSCT is a reliable novel test which is able to predict peak and endurance cycling performance from submaximal power, RPE and HRR in well-trained cyclists. As these parameters are able to detect meaningful changes more accurately than VO2max, the LSCT has the potential to monitor cycling performance with more precision than other current existing submaximal cycle protocols.

The interval shuttle run test for intermittent sport players: evaluation of reliability

The reliability of the interval shuttle run test (ISRT) as a submaximal and maximal field test to measure intermittent endurance capacity was examined. During the ISRT, participants alternately run for 30 seconds and walk for 15 seconds. The running speed is increased from 10 km·h−1 every 90 seconds until exhaustion. Within a 2-week period, 17 intermittent sport players (i.e., 10 men and 7 women) performed the ISRT twice in a sports hall under well-standardized conditions. Heart rates per speed and total number of runs were assessed as submaximal and maximal performance measures. With the exception of the heart rates at 10.0 km·h−1 for men and 10.0, 12.0, and 13.5 km·h−1 for women, zero lay within the 95% confidence interval of the mean differences, indicating that no bias existed between the outcome measures at the 2 test sessions (absolute reliability). The results illustrate that it is important to control for heart rate before the start of the ISRT. Relative reliability was high (intraclass correlation coefficient ≥ 0.86). We conclude that the reliability of the ISRT as a submaximal and maximal field test for intermittent sport players is supported by the results.

Allometric scaling of peak power output accurately predicts time trial performance and maximal oxygen consumption in trained cyclists

Objective The purpose of this study was to determine if peak power output (PPO) adjusted for body mass0.32 is able to accurately predict 40-km time trial (40-km TT) performance. Methods 45 trained male cyclists completed after familiarisation, a PPO test including respiratory gas analysis, and a 40-km TT. PPO, maximal oxygen consumption (VO2max) and 40-km TT time were measured. Relationships between 40-km TT performance and (I) absolute PPO (W) and VO2max (l/min), (II) relative PPO (W/kg) and VO2max (ml/min/kg) and (III) PPO and VO2max adjusted for body mass (W/kg0.32 and ml/min/kg0.32, respectively) were studied. Results The continuous ramp protocol resulted in a similar relationship between PPO and VO2max (r=0.96, p<0.0001) compared with a stepwise testing protocol but was associated with a lower standard error of the estimated when predicting VO2max. PPO adjusted for body mass (W/kg0.32) had the strongest relationship with 40-km TT performance (s) (r=−0.96, p<0.0001). Although significant relationships were also found between absolute (W) and/or relative PPO (W/kg) and 40-km TT performance (s), these relationships were significantly weaker than the relationship between 40-km TT performance and PPO adjusted for body mass (W/kg0.32) (p<0.0001). Conclusions VO2max can be accurately predicted from PPO when using a continuous ramp protocol, possibly even more accurately than when using a stepwise testing protocol. 40-km TT performance (s) in trained cyclists can be predicted most accurately by PPO adjusted for body mass (W/kg0.32). As both VO2max and 40-km TT performance can be accurately predicted from a PPO test, this suggests that (well)-trained cyclists can possibly be monitored more frequently and with fewer tests.