JOURNAL OF SPORTS SCIENCE & MEDICINE
DISCREPANCY BETWEEN TRAINING, COMPETITION AND LABORATORY MEASURES OF MAXIMUM HEART RATE IN NCAA DIVISION 2 DISTANCE RUNNERS
Katherine Semin1, Alvah C. Stahlnecker IV1, Kate Heelan1, Gregory A. Brown1, Brandon S. Shaw2 and Ina Shaw3
1University of Nebraska at Kearney, USA, 2Tshwane University of Technology, Republic of South Africa 3Vaal University of Technology, Republic of South Africa
© Journal of Sports Science and Medicine (2008) 7, 455 - 460
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|A percentage of either measured or predicted maximum heart rate
is commonly used to prescribe and measure exercise intensity. However, maximum
heart rate in athletes may be greater during competition or training than
during laboratory exercise testing. Thus, the aim of the present investigation
was to determine if endurance-trained runners train and compete at or above
laboratory measures of 'maximum' heart rate. Maximum heart rates were measured
utilising a treadmill graded exercise test (GXT) in a laboratory setting
using 10 female and 10 male National Collegiate Athletic Association (NCAA)
division 2 cross-country and distance event track athletes. Maximum training
and competition heart rates were measured during a high-intensity interval
training day (TR HR) and during competition (COMP HR) at an NCAA meet. TR
HR (207 ± 5.0 b·min-1; means ± SEM) and COMP HR (206 ± 4 b·min-1)
were significantly (p < 0.05) higher than maximum heart rates obtained
during the GXT (194 ± 2 b·min-1). The heart rate at the ventilatory
threshold measured in the laboratory occurred at 83.3 ± 2.5% of the heart
rate at VO2 max with no differences between the men and women.
However, the heart rate at the ventilatory threshold measured in the laboratory
was only 77% of the maximal COMP HR or TR HR. In order to optimize training-induced
adaptation, training intensity for NCAA division 2 distance event runners
should not be based on laboratory assessment of maximum heart rate, but
instead on maximum heart rate obtained either during training or during
Key words: Competition, heart rate, laboratory, performance, running, training.
|Successful performance in aerobic distance running is dependant
on the athlete's ability to cover a fixed distance in the shortest time
possible. To attain this objective, distance runners must train hard, yet
intelligently, to maximize the physiological adaptations derived from training
(Baechle and Earle, 2000).
An effective distance runner's program must include an exercise prescription
specifically developed for the individual athlete. In this regard, the regulation
of exercise intensity is critical to the success of each training session
and ultimately the entire training program since an exercise intensity set
too low does not induce the desired physiological adaptations while an exercise
intensity set too high results in fatigue and a premature end to training
sessions (Potteiger and Weber, 1994).
There are many different techniques for measuring exercise intensity during endurance training, including speed, percentage of maximal oxygen consumption (VO2max), or a measurement of heart rate (Jeukendrup and Diemen, 1998). Heart rate is commonly used when prescribing aerobic exercise intensity due to the assumption of a linear relationship between heart rate and oxygen consumption (VO2) (Boulay et al., 1997). The load of the circulatory system during exercise is usually determined based on the difference between heart rate during exercise and at rest and the assumption is that 60% to 90% of maximum heart rate is equivalent to 50% to 85% of VO2max (American College of Sports Medicine, 1990; Brooke and Hamley, 1972; Hoffman et al., 2001). Furthermore, the use of telemetric heart rate monitors enables a simple, non- invasive, and convenient method for the continuous measurement of heart rate during exercise (Jeukendrup and Diemen, 1998; Lambert et al., 1998). During graded exercise testing there is frequently a divergence from the linear heart rate - workload relationship, called the heart rate deflection point (HRDP) (Bodner and Rhodes, 2000; Brooke and Hamley, 1972). Identifying the HRDP may be useful when prescribing exercise intensity. For instance, Conconi et al. , 1982 observed that by monitoring the heart rate during incremental track running exercise one could estimate the lactate threshold by noting the change in the slope of the heart rate, but the accuracy of the HRDP for identifying the lactate threshold is debated (Bodner and Rhodes, 2000). With certain heart rate monitors the heart rate data from the exercise session can be conveniently transferred to a computer for post exercise evaluation and, if necessary, adjustments to the training program to achieve the appropriate exercise stimulus.
Testing of the athlete to determine individual physiological capabilities helps athletes and coaches identify areas in need of improvement and can be used in goal setting. Maximum heart rates may be predicted from many published equations such as age-predicted maximal heart rate equations in the absence of laboratory testing. Two such commonly used methods are the percentage of maximal heart rate method (American College of Sports Medicine, 1990) and the Karvonen method (Karvonen et al., 1957). However, such estimates of heart rate maximum have shortcomings when compared to laboratory testing due to factors including inter alia: age, pollution, medications, caffeine, smoking, certain disease conditions, mode of exercise and current fitness levels (O'Toole et al., 1998; Tsuji et al., 1996). In addition to this, there is variability in maximal heart rate measures dependant on the test applied or even across different settings (Kunduracioglu et al., 2007). It has also been established that there can be considerable differences in heart rate between competition and training, even when the training pace and distance are the same (Lambert et al., 1998). In contrast, Zhou et al., 1997 observed that during a short course triathlon, the athletes exercised at a heart rate that corresponded to their laboratory measured ventilatory threshold, suggesting that the identification of the heart rate corresponding to the ventilatory threshold can be used to determine an effective training and competition strategy. Furthermore, the relationship between running speed and heart rate can be easily established and monitored throughout a training period, and can be effectively used to monitor the effectiveness of the training program (Selley et al., 1995). However, the use of heart rate to determine exercise intensity is frequently based on a measurement of maximum heart rate, and there may be some disagreement between the measurement of maximal heart rate when performed in a laboratory compared to training or competition setting (Jeukendrup and Diemen, 1998; Lambert et al., 1998). Thus, the aim of the present investigation was to ascertain if endurance-trained runners train and compete at or above laboratory measures of maximum heart rate when compared to a high-intensity interval training day and during competition at a National Collegiate Athletic Association (NCAA) meet.
female (mean age: 20.1 years ± 7.8) and 10 male (mean age: 19.9 years ±
6.2) NCAA division 2 cross-country and distance event track athletes were
sampled from the University of Nebraska at Kearney. Prior to participation
in the investigation, all volunteers gave written informed consent and underwent
a screening history and physical examination and were allowed to discontinue
the study at any time. This investigation was approved by the Institutional
Review Board at the University of Nebraska at Kearney.
For descriptive purposes, the body composition was assessed on each subject using hydrostatic weighing. Body mass was measured to the nearest 0.01 kilogram (kg) using a digital platform scale (PS6600, Befour Inc, Saukville, WI, USA) and body height was measured to the nearest 0.25 centimetres (cm) measured using a stadiometer (216, SECA, Hanover, MD, USA). Underwater mass was recorded to the nearest 25 grams with an Autopsy Scale (Chatillion, Kew Gardens, NY, USA). Subjects performed six trials with the mean of the three highest mass trials used for subsequent calculations of body composition. Residual volume was measured in duplicate immediately before underwater weighing using an Nitrogen Gas Analyzer (Exertech, Dresbach, MN, USA) using the techniques of Wilmore et al., 1980 and the subjects exhaled to residual volume during the underwater weighing. After the determination of body density, percent body fat was calculated with the Brozek equation (Siri, 1961)
Laboratory maximum heart rates were measured utilising a treadmill (2300, Sensor Medics, Yorba Linda, California, USA) graded exercise test (GXT) during which the subjects ran at a self reported comfortable pace (12.9 km·h-1 ± 0.8) and the grade increased by 2.5% every two minutes, a graded exercise protocol similar to that used by Costill and Fox, 1969 and Maskud and Coutts, 1971 for evaluating VO2max in well trained runners. Ratings of Perceived Exertion (RPE) and heart rates were recorded every minute and when the subjects reached volitional exhaustion. Oxygen consumption was measured continuously throughout the graded exercise testing using a metabolic cart (2900, Sensor Medics, Yorba Linda, CA, USA) and the data for oxygen consumption was averaged over 15-second intervals. The ventilatory threshold for each subject was determined by noting the point where an abrupt increase in VE·VO2-1 occurred without a concomitant increase in VE·VCO2-1 as a measure of the lactate threshold (Haverty et al., 1988) and the heart rate measured at this point was considered to be the heart rate at ventilatory threshold. Under all conditions, heart rates were measured with heart rate monitors (610, Polar Electro, Oy, Finland) that measured heart rate continuously and averaged the data over five-second intervals. Maximum training heart rates (TR HR) were measured after warm-ups and during a 400 metre indoor (temperature of 23.9 degrees Celsius) interval training workout in which the subjects were instructed to run eight sets of 400 metres at a pace that was approximately five seconds faster per kilometre than their race pace with one minute of active recovery between each interval. The competition heart rates were measured during competition (COMP HR) at an outdoor NCAA meet (temperature of 22.8 degrees Celsius) with distances of six kilometres for the females and 10 kilometres for the males. Heart rates were measured first in the laboratory, then during competition, then in training and the subjects were prevented from observing their heart rate throughout all trials by covering the face of the wristwatch part of the heart rate monitor receiver with black tape.
Independent T-tests were used to evaluate gender differences in age, body height, body mass, body composition, VO2max, and heart rate at ventilatory threshold. The maximum heart rate data from laboratory, training, and competition were analyzed via a two-factor (gender by condition) repeated measures analysis of variance (ANOVA) using commercial software (SigmaStat 3, Systat Inc, Point Richmond, CA, USA) at a significance level of 95% or p < 0.05. When significant interactions were observed, specific mean differences were identified using a Newman-Keuls multiple comparison test. Data are presented as means ± SEM.
subject descriptive data are presented in Table
1. During the laboratory testing, the heart rate at the ventilatory
threshold occurred at 83.3 ± 2.5% of VO2max with no differences
between the men and women. The women completed their six kilometre competition
trial in 23.28 minutes (± 0.56) and the men completed their 10 kilometre
competition in 34.4 minutes (± 0.61).
finding of this experiment is that the maximal heart rate measured during
a treadmill graded exercise test is considerably lower than the maximal
heart rate obtained during either competition or during endurance interval
training in distance runners. These data suggest that the exercise setting
in which heart rates are measured should be considered when maximal heart
rates are used for prescribing training intensity.
possible reason for the athletes obtaining higher heart rate maximum levels
during the high-intensity interval training day and during competition
when compared to the treadmill GXT in a laboratory setting could be due
to differences in temperature during test conditions (Potteiger and Weber,
1994). In this regard, temperature is always a controlling
factor for chemical reactions and since heart rate is a function of chemical
processes, when temperatures increase upward from 21 degrees Celsius,
heart rate increases in a correlative manner by about one beat per minute.
In the case of laboratory testing, the temperatures during the testing
were controlled at between 23 and 25 degrees Celsius whereas during training
and competition, the temperatures were not as controlled or
measured and may be much higher than during laboratory testing resulting
in increased heart rate levels. However, the temperature in the training
facility (23.9 degrees Celsius) was very similar to the temperature in
the laboratory, so it seems unlikely that differences in temperature would
account for the differences in maximal heart rate. For the same reasons
as increased temperature, a higher relative humidity will increase maximal
heart rate. Further, during training and competition, runners typically
lose over one kilogram of water per hour. This results in blood volume
decreases and less blood is pumped by the heart per beat. Specifically,
for every 1% loss in body weight due to dehydration, heart rate increases
by approximately seven beats per minute (Lambert et al., 1998).
|The findings of the present investigation cast doubt on the interchangeability of laboratory and field tests. Thus, in order to optimize training-induced adaptation, training intensity for NCAA division 2 distance event runners should not be based on laboratory assessment of maximum heart rate, but instead on maximum heart rate measures obtained either during training or during competition as these conditions better represent "real-life" situations than does a laboratory setting.|
|The authors are grateful to the HPERLS Department, University of Nebraska at Kearney, United States of America for the use of their Human Performance Laboratory.|
Katherine L. BAILEY (SEMIN)
Employment: Student in the Physical Therapy Program - University of Nebraska Medical Center.
Degree: Bachelor of Science Exercise Science with Sports Nutrition Option.
Research interests: Fitness, physical activity, rehabilitation.
Alvah Carl STAHLNECKER IV
Employment: Student - University of Nebraska Medical Center College of Pharmacy.
Degree: Bachelor of Science in Exercise Science.
Research interests: Pharmacology, exercise and cardiovascular disease.
Kate A. HEELAN
Employment: Associate Professor - University of Nebraska at Kearney.
Degree: PhD Exercise Science.
Research interests: Obesity prevention, physical activity, children.
Gregory A. BROWN
Employment: Associate Professor - University of Nebraska at Kearney.
Degree: PhD Health and Human Performance.
Research interests: Obesity, endocrinology of obesity and hunger, exercise and appetite regulation.
Brandon S. SHAW
Employment: Lecturer - Tshwane University of Technology.
Degree: PhD Biokinetics.
Research interests: Prevention and treatment of metabolic diseases, exercise and hypokinetic disease.
Employment: Lecturer - Vaal University of Technology.
Degree: PhD Biokinetics.
Research interests: Aetiology of non-communicable diseases, exercise and weight control, obesity.