ArticlePDF Available

Physiological responses to walking with hand weights, wrist weights, and ankle weights

Authors:

Abstract

To compare the blood pressure (BP) responses to exercise with 1.36 kg (3.0 lb) hand-held weights (HW), wrist weights (WW), and ankle weights (AW), 12 sedentary males (20.8 +/- 1.2 yr) completed three randomly assigned treadmill exercises at 75% maximum heart rate (HR) reserve. Systolic and diastolic BPs among HW (181.2 +/- 21.9 and 73.2 +/- 7.9 mm Hg), WW (180.1 +/- 27.2 and 71.0 +/- 10.1 mm Hg), and AW (183.8 +/- 26.8 and 71.7 +/- 7.8 mm Hg) were not significantly different (P greater than 0.05). When compared to exercise with no weights (NW), only the diastolic BP for HW was significantly different (+4.4 mm Hg, P less than 0.05). To evaluate the energy cost of exercise with HW, WW, and AW, subjects completed a fourth exercise at constant treadmill speed (6.3 +/- 0.3 km.h-1) and grade (6.3 +/- 1.4%). Oxygen uptake and HR responses were greater (P less than 0.01) for HW (30.4 +/- 0.8 ml.min-1.kg-1; 160.6 +/- 4.0 beats.min-1), WW (30.4 +/- 0.9 ml.min-1.kg-1; 159.7 +/- 4.6 beats.min-1), and AW (29.0 +/- 0.7 ml.min-1.kg-1; 154.6 +/- 4.4 beats.min-1) than for exercise with NW (26.6 +/- 0.7 ml-min-1.kg-1; 147.0 +/- 3.8 beats.min-1). Oxygen uptake and HRs for HW and WW were greater than for AW (P less than 0.05). Ratings of perceived exertion (Borg scale for NW (11.7 +/- 1.8), HW (12.1 +/- 2.0), WW (12.2 +/- 1.8), and AW (12.3 +/- 1.8) were not significantly different (P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
... To intensify walking exercise there are several options for the walker; increase speed (Ainsworth et al., 2011), increase gradient (Graves, Pollock, Montain, Jackson & O'Keefe, 1987;Graves, Martin, Miltenberger & Pollock, 1988), walk on less stable surfaces such as sand (Lejeune, Willems & Heglund, 1998), carry additional weight (Auble & Schwartz, 1991), or any combination. ...
... Comparisons between walking with or without additional weight has been conducted on a variety of populations, employing a range of different speeds, and using between 0.45kg and 2.27kg per hand. Some studies have used an incline to achieve a target exercise intensity (Graves et al., 1987;Graves et al., 1988), others have specified a particular arm action very different to a normal walking swing (Auble, Schwartz & Robertson, 1987). In each case the authors have anticipated an increase in the energy cost and perceived exertion of the exercise, and expected to observe elevated heart rate and blood pressure as a direct result of the additional weight. ...
... In a similar study involving sedentary subjects initially exercising at 60%HHR, Graves et al. (1988) reported a 3.8ml/kg/min increase in V  O2 when 1.36kg were added to each hand (p<0.01). However, this was not accompanied by a significant increase in RPE, which remained in the range 11.7-12.3 ...
Thesis
Exploring the physiological adaptations when hand-held weights are incorporated into a six-week programme of regular walking.
... While various exercise interventions are commonly practiced among older adults living in the community, it has been reported that improving physical balance is most important for fall prevention. 1 Falls among older adults can be reduced by exercise interventions, particularly balance improvement exercises and various types of combination exercises. 2 It has been reported that instructor-led gymnastics classrooms are safer and more effective than self-directed efforts and self-judgment, and are more suitable for improving physical function than exercising at home. 3 However, widespread distribution of such classrooms as part of health safeguarding cannot be expected in the near future because of shortfalls in systems, facilities, sta ng, and cost, including the cost performance index. ...
... Wearing ankle weights (AWs) on the ankles while walking is reported as a method for increasing physical activity intensity that has been used [1]. This equipment is widely available in sports stores as consumer products, and is commonly used for lower limb training by younger adults. ...
Preprint
Full-text available
Background Since the emergence of Coronavirus disease 2019 (COVID-19), safety management in gymnastics classrooms has been difficult. As a result, healthy older adults are more likely to voluntarily refrain from attending because of fear of contracting COVID-19, and thus engage in less exercise. In this context, it is important to develop methods for self-prevention of frailty that can be conducted safely and easily at home. We examined the effectiveness of providing ankle weights to older adults as a frailty prevention device. Methods All participants were 50–90 years old and were screened for falls using the Motor Fitness Scale (MFS). Participants were divided into two groups (≤ 70 and ≥ 71 years old) and analyzed. We rented ankle weights for 3 months to older adults in the community and evaluated changes in physical and motor function before and after wearing them. A total of 75 people who responded to the call for participants used ankle weights for 3 months, and underwent various measures of physical condition, cognitive condition, and performance (body composition, grip strength, standing on one leg with eyes open, 30-second chair stand test [CS-30], timed up-and-go test [TUG], walking speed, body sway measurement, and the Japanese version of Montreal Cognitive Assessment [MOCA-J]) before and 3 months after wearing ankle weights. Results CS-30 performance improved in both younger and older participants. Conclusions CS-30 reflects lower limb/trunk muscle strength and can be used as an index of fall risk. Our results suggest that wearing ankle weights can be recommended as a fall-prevention measure. Trial registration University hospital Medical Information Network ID 000038073) and registration date at April 14th 2020
... We sought to compare measures of EE, as a measure of true physiological load, to heart-rate (HR), as a general indicator of the total psycho-physiological load experienced by players, to determine whether AG in HMD truly increased energy expenditure or merely increased stress from a heightened emotional engagement in the game. To further highlight any potential discrepancy between EE and HR, we included an additional condition known to promote EE simply by adding weight at the wrists [18]. Finally, because most AG are designed using levels of incremental difficulty, a secondary aim of this study was to assess at which level, if any, sufficient levels of physical activity were achieved, and thus provide a basis for future AG developments in HMD. ...
... However, adding weights at the wrists induced EE comparable to W6 only at higher AG levels, and further underscored the comparatively greater response in HR% than EE. Still, we observed that adding wrist-worn weights induced a large change in the time spent at or above walking EE, especially at the higher levels of the game, and thus, this simple physical constraint could be used increase the intensity of physical exercise during AG as is commonly done for conventional exercise [18]. Therefore, future studies could evaluate the specific role of task-related constraints (rules changes, feedback, cooperative vs. competitive situations) or modified environmental conditions (ambient temperature, oxygen partial pressure) to increase energy expenditure for health promotion purposes. ...
Article
Full-text available
Virtual reality using head-mounted displays (HMD) could provide enhanced physical load during active gaming (AG) compared to traditional displays. We aimed to compare the physical load elicited by conventional exercise and AG with an HMD. We measured energy expenditure (EE) and heart rate (HR) in nine healthy men (age: 27 ± 5 years) performing three testing components in a randomised order: walking at 6 km/h (W6), AG, and AG with an additional constraint (AGW; wrist-worn weights). Although we found that HR was not significantly different between W6 and the two modes of AG, actual energy expenditure was consistently lower in AG and AGW compared to W6. We observed that playing AG with wrist-worn weights could be used as a means of increasing energy expenditure only at maximum game level, but ineffective otherwise. Our findings indicate that AG in an HMD may not provide a sufficient stimulus to meet recommended physical activity levels despite increased psychophysiological load. The differential outcomes of measures of HR and EE indicates that HR should not be used as an indicator of EE in AG. Yet, adding a simple constraint (wrist-worn weights) proved to be a simple and effective measure to increase EE during AG.
... The contribution of other factors such as army training, skills and physical built up of the soldiers in this direction are inseparable. Carriage of load in hand increases the energy cost (Graves et al., 1988) and is considered worst in terms of physiological efficiency (Datta and Ramanathan, 1971). Malhotra and Sengupta (1965) observed that oxygen consumption for load carrying by hand was 34% more than for carrying the same load in the rucksack mode. ...
... Carrying rifle (4.2 kg) and LMG (6.8 kg) in hand could definitely have contributed a reasonable increase in energy consumption in our study. Graves et al. (1988) found that the energy expenditure of walking exercise can be increased by approximately 1-MET (multiple of the resting metabolic rate) when 1.36 kg load is carried in hand. Some isometric hand gripping associated with hand carried weight may result in a small increase in diastolic blood pressure also. ...
Article
Full-text available
Physiological responses of soldiers while carrying different loads were studied to suggest optimum load that can be carried by an Indian infantry soldier comfortably at level ground at two different walking speeds. Ten physically fit male infantry soldiers walked at 3.5 and 4.5 km h À1 each on treadmill without and with loads of 4.4, 10.7, 17.0, 21.4, 32.4 and 40 kg for 10 min duration. Heart rate (HR), minute ventilation (V E), oxygen consumption (VO 2) and energy expenditure (EE) were determined using K4b 2 system. A linear increase in HR, V E , VO 2 and EE with increasing external load was observed. The effect is more pronounced with speed than load. Based on physiological limit of 35% VO 2 max and linear regression equation loads of 36.1 and 21.3 kg are suggested as permissible for carriage on level ground at 3.5 and 4.5 km h À1 speeds, respectively. This combination of weight and speed is expected to improve the load carrying efficiency of the soldiers. Relevance to industry: Developing countries mostly do not have load carriage standards of their own, either for Industry or Military. Results of this study will be of immense help in developing their own standards or to make use of these recommendations for the similar kind of population under specified conditions.
... Wearing ankle weights (AWs) while walking has been reported to be an effective method for increasing the intensity of physical activity [9]. AWs are widely available in sporting goods stores, and are often used by younger adults for lower limb training. ...
Article
Full-text available
Since the start of the COVID-19 pandemic, many healthy older adults have been less willing to engage in group exercise for fear of contracting this illness. Therefore, there is a need for an effective home-based exercise program to prevent frailty in the elderly. In this study, we assessed the effectiveness of ankle weights as a frailty prevention device for older adults. The study participants were aged 50-90 years and were screened for falls using the Motor Fitness Scale. Participants were divided into two age groups (≤70 and >70 years) for analysis. Older community-dwelling adults were invited to use ankle weights for 3 months. Seventy-five people responded to the invitation. Physical and cognitive status and performance (body composition, grip strength, standing on one leg with eyes open, the 30 s chair stand test (CS-30), Timed Up and Go test, walking speed, body sway, Japanese version of the Montreal Cognitive Assessment) were assessed before and after 3 months of intervention. CS-30 performance improved during the study. CS-30 reflects lower limb/trunk muscle strength and can be used to indicate the risk of falls. Wearing ankle weights can be recommended for strengthening the muscles of the lower limb and trunk in the elderly.
... Greater muscular activity of the arm and shoulder carrying rifle may be the key factor behind excess energy cost observed with the distributed mode in the present study. Graves et al. [37] compared a hand held weight to wrist weight and ankle loads and found a 1.36 kg increase in hand or wrist weight increases the energy cost. This observation helps to understand how rifle carriage in the hand can raise the energy expenditure of the participant up to certain extent compared to free hand movements. ...
Article
Full-text available
Background: The present study was undertaken to determine the effect of different uphill and downhill gradients on cardiorespiratory and metabolic responses of soldiers while carrying heavy military loads in two different modes. Methods: Eight physically fit male soldiers with a mean age 32.0 ± 2.0 years, a mean height of 169.5 ± 4.9 cm, and a mean weight of 63.8 ± 8.4 kg volunteered for this study. Each volunteer completed treadmill walking trials at a speed of 3.5 km/h while carrying no external load, 31.4 kg load in a distributed mode (existing load carriage ensembles) and compact mode (new back pack) over 5 different downhill and uphill gradients (- 5, - 10%, 0, 5, 10%) for 6 min at each gradient. During the walking trials, heart rate (HR), oxygen uptake (VO2), respiratory frequency (RF) and energy expenditure (EE) were determined by the process of breath-by-breath gas analysis using a K4b2 system. The average of the last 2 min data from each 6 min walking trial for each individual was subjected to statistical analysis. Results: All parameters (HR, VO2, RF, and EE) gradually increased with the change in gradient from downhill to level to uphill. The distributed mode showed higher values compared to compact mode for all gradients, e.g., for VO2, there was a 10.7, 7.4, 5.1, 28.2 and 18.7% increase in the distributed mode across the 5 different gradients. Conclusion: It can be concluded from the present study that the compact mode of load carriage is more beneficial than the distributed mode in terms of cardiorespiratory responses while walking on downhill and uphill surfaces with a 31.4 kg load.
... internal load [6]. Indeed, in the lasts years the session RPE was used to verify the trainig program [7] and avoid the overtraining (arbitrary units over than 600 in one week; [8] [9]) in several sport. ...
Article
Full-text available
The Rate of Perceived Exertion scale was widly used in monitoring training session but the feasability of this approach was not verified in skateboarding training or competition. Thus, the purpose of this brief report was the assessment of a skateboarder using the Rate of Perceived Exertion. Nine months of conditioning about a professional skater were collected after each session. The Rate of Perceived Exertion was interviewed, also, after the most important competition day. Furthermore, the internal training load was evaluated using the indication proposed in scientific community. During the first period of training, the training load was similar than the value obtained in the most official competition of the season. The mean value of Rate of Perceived Exertion collected during the training session was similar to the results declared during the competition. The value of training load in this professional skater was simialr to other professional athletes. The trainer could find important practical implication such as the statement that the skater did not reach, on average, the level of overtraining. Further studies could improve the assessment using more detailed stratification about the kind of condition and about the physiological parameters.
Article
Aims The world is facing a significant crisis related to physical inactivity and obesity. These growing public health burdens demand the development of innovation both in terms of health initiatives and products aimed at stabilizing and reversing the negative trends reported in epidemiological literature. Wearable weights have been developed to address this issue but research to date has not tested the efficacy of these products. Methods Seventeen (11 female, 6 male, mean age = 24 years, mean BMI = 25, mean VO2 = 43 ml/kg/min) healthy and physically active volunteers completed trials of treadmill exercise at slow and brisk walking speeds with varied combinations of upper and lower body wearable weights (no weights, arm weights, leg weights, and arm plus leg weights). Primary variables of interest included heart rate, oxygen consumption, and perceived exertion. Results Data were analyzed using ANOVA and pairwise comparisons. Analyses indicated that oxygen consumption increased significantly when weights were worn (P < 0.05), while RPE was largely unaffected by wearing weights (P > 0.05 for most comparisons). The magnitude of increased energy expenditure was approximately 10%. Conclusion Findings suggest exercising at low and moderate intensities while wearing weights that can be concealed under clothing may be an effective strategy for increasing energy expenditure and weight management.
Article
Calibration is the process by which the execution of actions becomes scaled to the (changing) relationship between environmental features and the actor’s action capabilities. Though much research has investigated how individuals calibrate to perturbed optic flow, it remains unclear how different experimental factors contribute to the magnitude of calibration transfer. In the present study, we assessed how testing environment (Experiment 1), an adapted pretest-calibration-posttest design (Experiment 2), and bilateral ankle loading (Experiment 3) affected the magnitude of calibration to perturbed optic flow. We found that calibration transferred analogously to real-world and virtual environments. Although the magnitude of calibration transfer found here was greater than that reported by previous researchers, it was evident that calibration occurred rapidly and quickly plateaued, further supporting the claim that calibration is often incomplete despite continued calibration trials. We also saw an asymmetry in calibration magnitude, which may be due to a lack of appropriate perceptual-motor scaling prior to calibration. The implications of these findings for the assessment of distance perception and calibration in real-world and virtual environments are discussed.
Thesis
La charge de travail peut être évaluée de différentes façons. Des méthodes objectives (pression artérielle et fréquence cardiaque) et/ou subjectives (échelle de Borg CR10) ont été utilisées tant en laboratoire que sur le terrain. L'étude en laboratoire quantifie les astreintes cardiovasculaires et subjectives développées par 30 sujets jeunes (15 femmes et 15 hommes) au cours de 7 tests d'endurance statique appliqués à différents groupes musculaires du membre supérieur dominant. Les paramètres objectifs et subjectifs augmentent linéairement au cours des tests jusqu'à leur maximum. Les coûts cardiaque et tensionnel maxima sont respectivement de 20 à 36 bpm et de 22 à 33 mm Hg. Le coût subjectif est de 10 sur l'échelle de Borg. L'étude de terrain s'est effectuée dans un abattoir de porcs. Les astreintes subjectives recueillies pendant 5 moments prédéfinis des 8 heures de travail sont associées à un enregistrement vidéo pour l'étude des postes de 11 désosseurs et de 10 pareurs (7 femmes et 14 hommes). Les résultats ont permis de préciser les plaintes des salariés, les postes ressentis comme les plus pénibles et l'effet "fatigue" au cours de la journée. Dans ces 2 études, la comparaison de données objectives et subjectives, permet d'appréhender les intérêts et les limites des échelles de Borg comme méthode d'évaluation ergonomique de la charge de travail.
Article
Full-text available
1. Skinfold thickness, body circumferences and body density were measured in samples of 308 and ninety-five adult men ranging in age from 18 to 61 years. 2. Using the sample of 308 men, multiple regression equations were calculated to estimate body density using either the quadratic or log form of the sum of skinfolds, in combination with age, waist and forearm circumference. 3. The multiple correlations for the equations exceeded 0.90 with standard errors of approximately ±0.0073 g/ml. 4. The regression equations were cross validated on the second sample of ninety-five men. The correlations between predicted and laboratory-determined body density exceeded 0.90 with standard errors of approximately 0.0077 g/ml. 5. The regression equations were shown to be valid for adult men varying in age and fatness.
Article
Full-text available
Ten male subjects exercised maximally on a bicycle ergometer with legs alone and with arm work combined with maximal leg work. Vo2 max was 10% higher with combined work than with legs-only work (p <.002). This result demonstrates that Vo2 max is a function of the mass of muscle engaged in the exercise. It also casts considerable doubt on the hypothesis that Vo2 max is limited by the ability of the heart to pump blood.
Article
An intact work crew of nine weather observers (ages 19-32 y) wore weighted ankle spats for 20 continuous days for 7·5-7·9 h each day on the job while performing normal duties and for an equal amount of time on days off. Four observers continued wear for another 20 days. Weights on each ankle were 2·25 kg for two days and 3·0 kg thereafter. Oxygen uptake (V˙O2) and heart rate (HR) were determined before and after conditioning at six submaximal work loads: level walking at 1·12 and 1·56ms, with and without ankle weights, and crgometer cycling at two work loads selected to elicit final HR near 150 and 180 beat min. Submaximal HR declined and predicted aerobic power at HR = 180 (PAP180) increased throughout the conditioning period, but significance was reached only after six weeks (mean HR decrease = 18 beat min, p
Article
Thirty-two subjects marched 20 km with 3 different back loads; 20, 25 and 30 kg. Their heart rate, rectal temperature and VO 2max, immediately following the march, were compared to initial values. A mean drop of more than 20% in VO 2max was found in the group carrying the 30 kg load, while no significant decrease in VO 2max occurred in the subjects carrying 20 and 25 kg loads. No correlation was found between the change in VO 2max and the weight of the subjects or the percentage of the load from the body weight. Since those who carried the 30 kg load were in excellent physical condition (VO 2max more than 50 ml O 2/min x kg B.W.) and those who carried the 25 kg load were only of a good one (VO 2max 40-49 ml O 2/min x kg B.W.), it is suggested that to avoid significant decrease in VO 2max, the maximal back load carried by an individual in good physical condition for long distances under field conditions, should not exceed 25 kg.
Article
Twenty young men marched 6 and 12 km with a well-fitted back-pack load of 30 or 35 kg. Each subject served as his own control. No significant increase in mean heart rate, rectal temperature, or decrease in mean VO2 max and serum levels of glucose and muscle enzymes were recorded in the groups marching 6 km with 30 and 35 kg. Significant differences in the increases in mean heart rate, the decreases in VO2 max and the changes in blood glucose were noted between the two groups carrying 30 and 35 kg for 12 km. These significant differences were also supported by the subjective feelings of the volunteers. The present study shows the optimal back-pack load for healthy young men, marching at 6 km/hr on a paved level road to be 30 kg for 12 km and 35 kg for 6 km without considering the task too difficult and with no significant decrease in VO2 max. The results are relevant to hiking, rescue assignments, and military missions.
Article
Physical conditioning using weighted ankle spats was evaluated in eight men in the age range 33 to 45 years (mean, 38.4). Evaluation consisted of pretraining and posttraining heart rate (HR) and oxygen uptake (VO2) responses to five submaximal work loads: cycling six minutes at 600 kilopond meter per minute (kpm/min); level walking for ten minutes at both 4.0 and 5.6 km/hr with and without a 1.5-kg weight spat added to each ankle. After the initial baseline evaluation, subjects wore 1.5-kg weight spats on both ankles for three weeks and were reevaluated; during the next three-week period weight was increased to 2.25 kg per ankle. Following the six-week evaluation period, subjects did not wear ankle spats, and detraining was evaluated after three weeks. A control group of four subjects was evaluated at these same submaximal work loads on three different occasions with three-week periods between evaluations. The experimental group wore the spats about 13.5 hours per day and averaged 6.85 km/day (4.25 miles per day) during training. After six weeks of training, submaximal HR decreased 6 to 9 beats per minute (P smaller than 0.05) from pretraining values for all five submaximal work loads; predicted VO2 max and predicted work capacity to achieve a HR of 170 beats per minute increased by approximately 10%. Detraining submaximal HR responses increased slightly, but not significantly, from post six-week training responses. Control group submaximal responses were unchanged between evaluations. It was concluded that individuals who initially possess a low level of cardiorespiratory fitness may have a low threshold for training. Thus, leg weight conditioning may be extremely useful for rehabilitation of patients and for sedentary middle-aged men as special adaptation prio to more high intensity training.
Article
Fifteen highly trained men performed treadmill running at 12 km X h-1 to determine the effect of lower extremity loading on measures for seven temporal and kinematic descriptors of the running cycle, the mechanical work done on the lower extremity, oxygen consumption (VO2) and heart rate. Five load conditions (no added load and loads of 0.50 kg and 1.00 kg added to either the thighs or feet) were examined. The results demonstrated that VO2 and heart rate increased as load was increased on both the thighs and feet. All changes were statistically significant except for the heart rate changes due to thigh loading. The increases in VO2 due to foot loading--approximately 7.2% per kg of load--were nearly twice as great as those due to thigh loading. The results also demonstrated that 1.00 kg added to the feet produced small but significant increases in stride length (1.4 cm), swing time (9 ms), and flight time (6 ms) and a decrease in peak ankle velocity (0.23 m X s-1). No other load condition resulted in significant changes in any of the temporal and kinematic variables. The results for mechanical work demonstrated that significant increases in the work done on the leg were produced by the loading but that these increases were limited to the loaded segments. Consistent with the data for oxygen consumption and heart rate, mechanical work was increased to a greater extent by foot loading than by thigh loading. It was concluded from these results that the increased physiological demand was directly related to the mechanical work increases, which in turn were attributed to the increased inertia of the loaded segments rather than modifications in the kinematics of the lower extremity movements.
Article
This study evaluated the hypothesis that the isometric stress of load carrying augments the dynamic exercise response seen on the treadmill, and estimated the magnitude of this effect on heart rate and blood pressure for several methods of carrying the same load. Thirteen healthy subjects carried 40 lb in the right hand (H), 40 lb on the back (B), 20 lb in each hand (D) and no weight (N) while walking for 3 minutes on the treadmill at a grade of 0 at 1.7 miles/ hour. A statistically significant increase in the rate of rise and peak levels of systolic blood pressure, heart rate, estimated mean blood pressure, the product of estimated mean blood pressure and heart rate and systolic blood pressure-heart rate product was shown when task H was compared with tasks B, D and N. Values for tasks D and B did not differ significantly.The effects of isometric and dynamic exercise combined were greater than those of dynamic exercise alone. An effective technique of load distribution reduced the rate of increase in blood pressure, heart rate and the peak attained during dynamic exercise, thereby suggesting a lower level of myocardial oxygen consumption for a given weight-carrying task. These results can be applied to evaluation of patients with heart disease and estimation of their exercise tolerance.
Article
. Perceived exertion was measured using a linear grading scale, in three healthy males performing paired patterns of continuous and intermittent exercise with the same average power output. Intermittent exercise with work periods of 10 sec. alternating with recovery periods of loadless pedalling for 30 sec. was associated with lower perceived exertion grades than when work periods were 30 or 120 sec. Perceived exertion, oxygen intake, ventilation, heart rate, and blood lactate concentration were all significantly higher for intermittent exercise than for continuous exercise with the same average power output. The relationships between perceived exertion and the physiological variables was the same for the two forms of exercise despite widely different mechanical stresses on the legs. Mechanical factors were therefore thought to make a relatively unimportant contribution to perceived exertion over the range of exercise intensities studied.—The high degree of correlation between perceived exertion and the measured physiological variables suggests a wider use of exertion grading in field studies.