The study investigated physiological responses during 2-km walking at a certain intensity of a previously performed maximal exercise test where moderate perceived exertion was reported. Twenty seniors were examined by an incremental walking treadmill test to obtain maximal oxygen uptake (VO2max). A submaximal 2-km walking test was applied 1 wk later. The corresponding moderate perceived exertion (4 on the CR-10 scale) during the VO2max test was applied to the 2-km treadmill test. Moderate exertion (mean rating of perceived exertion [RPE]: 4 ± 1) led to 76% ± 8% of VO2max and 79% ± 6% of maximal heart rate. RPE values drifted with a significant time effect (p = .001, ηp = .58) during the 2-km test from 3 ± 0.7 to 4.6 ± 0.8. Total energy expenditure (EE) was 3.3 ± 0.5 kcal/kg. No gender differences in ventilatory, heart-rate, or EE data occurred. Brisk walking at moderate RPE of 3–5 would lead to a beneficial physiological response during endurance training and a weekly EE of nearly 1,200 kcal when exercising 5 times/wk for 30 min.
Lars Donath, Lukas Zahner, Mareike Cordes, Henner Hanssen, Arno Schmidt-Trucksäss and Oliver Faude
Paul G. Montgomery, David B. Pyne and Clare L. Minahan
To characterize the physical and physiological responses during different basketball practice drills and games.
Male basketball players (n = 11; 19.1 ± 2.1 y, 1.91 ± 0.09 m, 87.9 ± 15.1 kg; mean ± SD) completed offensive and defensive practice drills, half court 5on5 scrimmage play, and competitive games. Heart rate, VO2 and triaxial accelerometer data (physical demand) were normalized for individual participation time. Data were log-transformed and differences between drills and games standardized for interpretation of magnitudes and reported with the effect size (ES) statistic.
There was no substantial difference in the physical or physiological variables between offensive and defensive drills; physical load (9.5%; 90% confidence limits ±45); mean heart rate (-2.4%; ±4.2); peak heart rate (-0.9%; ±3.4); and VO2 (–5.7%; ±9.1). Physical load was moderately greater in game play compared with a 5on5 scrimmage (85.2%; ±40.5); with a higher mean heart rate (12.4%; ±5.4). The oxygen demand for live play was substantially larger than 5on5 (30.6%; ±15.6).
Defensive and offensive drills during basketball practice have similar physiological responses and physical demand. Live play is substantially more demanding than a 5on5 scrimmage in both physical and physiological attributes. Accelerometers and predicted oxygen cost from heart rate monitoring systems are useful for differentiating the practice and competition demands of basketball.
Gerhard Tschakert and Peter Hofmann
High-intensity intermittent exercise (HIIE) has been applied in competitive sports for more than 100 years. In the last decades, interval studies revealed a multitude of beneficial effects in various subjects despite a large variety of exercise prescriptions. Therefore, one could assume that an accurate prescription of HIIE is not relevant. However, the manipulation of HIIE variables (peak workload and peak-workload duration, mean workload, intensity and duration of recovery, number of intervals) directly affects the acute physiological responses during exercise leading to specific medium- and long-term training adaptations. The diversity of intermittent-exercise regimens applied in different studies may suggest that the acute physiological mechanisms during HIIE forced by particular exercise prescriptions are not clear in detail or not taken into consideration. A standardized and consistent approach to the prescription and classification of HIIE is still missing. An optimal and individual setting of the HIIE variables requires the consideration of the physiological responses elicited by the HIIE regimen. In this regard, particularly the intensities and durations of the peak-workload phases are highly relevant since these variables are primarily responsible for the metabolic processes during HIIE in the working muscle (eg, lactate metabolism). In addition, the way of prescribing exercise intensity also markedly influences acute metabolic and cardiorespiratory responses. Turn-point or threshold models are suggested to be more appropriate and accurate to prescribe HIIE intensity than using percentages of maximal heart rate or maximal oxygen uptake.
John G. Seifert, Greg L. Paul, Dennis E. Eddy and Robert Murray
The effects of preexercise hyperinsulinemia on exercising plasma glucose, plasma insulin, and metabolic responses were assessed during 50 min cycling at 62%
Jerry Mayo, Brian Lyons, Kendal Honea, John Alvarez and Richard Byrum
Rehabilitation specialists should understand cardiovascular responses to different movement patterns.
To investigate physiological responses to forward- (FM), backward- (BM), and lateral-motion (LM) exercise at self-selected intensities.
Within-subjects design to test independent variable, movement pattern; repeated-measures ANOVA to analyze oxygen consumption (VO2), heart rate (HR), respiratory-exchange ratio (RER), and ratings of perceived exertion (RPE).
10 healthy women.
VO2 and HR were significantly higher during LM than during FM and BM exercise. The respective VO2 (ml · kg · min–1) and HR (beats/min) values for each condition were FM 25.19 ± 3.6, 142 ± 11; BM 24.24 ± 2.7, 145 ± 12; and LM 30.5 ± 4.6, 160 ± 13. No differences were observed for RER or RPE.
At self-selected intensities all 3 modes met criteria for maintaining cardiovascular fitness. Practitioners can use these results to develop rehabilitation programs based on clients’ perception and level of discomfort
William M. Bertucci, Andrew C. Betik, Sebastien Duc and Frederic Grappe
This study was designed to examine the biomechanical and physiological responses between cycling on the Axiom stationary ergometer (Axiom, Elite, Fontaniva, Italy) vs. field conditions for both uphill and level ground cycling. Nine cyclists performed cycling bouts in the laboratory on an Axiom stationary ergometer and on their personal road bikes in actual road cycling conditions in the field with three pedaling cadences during uphill and level cycling. Gross efficiency and cycling economy were lower (–10%) for the Axiom stationary ergometer compared with the field. The preferred pedaling cadence was higher for the Axiom stationary ergometer conditions compared with the field conditions only for uphill cycling. Our data suggests that simulated cycling using the Axiom stationary ergometer differs from actual cycling in the field. These results should be taken into account notably for improving the precision of the model of cycling performance, and when it is necessary to compare two cycling test conditions (field/laboratory, using different ergometers).
Renee Newcomer Appaneal, Frank M. Perna and Kevin T. Larkin
Features of posttraumatic distress have been associated with treatment noncompliance and delayed surgical recovery among general medical and trauma populations. Although cognitive-affective and behavioral features of posttraumatic distress have been demonstrated among adult and adolescent athletes with injuries, physiological responses associated with posttraumatic distress have not yet been examined in this population. The objective of this study was to examine psychophysiological stress reactivity to orthopedic trauma among male athletes who sustained a severe sport injury. Athletes with injuries (n= 7) and non-injured athlete controls (n= 5) completed self-report measures of psychological distress and were then shown injury video footage while heart rate and skin conductance measures were recorded. After exposure to orthopedic trauma-related video footage, athletes with injuries demonstrated significantly greater skin conductance reactivity and subjective distress compared to controls. As demonstrated among other medical and trauma populations, athletes with injuries exhibit exaggerated stress reactivity profiles when primed with orthopedic trauma stimuli.
Richard B. Kreider
The physiological effects of endurance exercise have been a primary area of research in exercise science for many years. This research has led not only to a greater understanding of human physiology but also the limits of human performance. This is especially true regarding the effects of endurance exercise on energy metabolism and nutrition. However, as science has attempted to understand the physiological and nutritional demands of endurance exercise lasting 1 to 3 hours, an increasing number of athletes have begun participating in ultraendurance events lasting 4 to 24 hours. Consequently some research groups are now investigating the physiological responses to ultraendurance training and performance. This paper reviews the literature on ultraendurance performance and discusses nutritional factors that may affect bioenergetic, thermoregulatory, endocrinological, and hematological responses to ultraendurance performance.
Lawrence E. Armstrong, Roger W. Hubbard, E. Wayne Askew, Jane P. De Luca, Catherine O'Brien, Angela Pasqualicchio and Ralph P. Francesconi
This investigation examined whether low sodium (Na+) (LNA; 68 mEq Na+·d-1) or moderate Na+ (MNA; 137 mEq Na+.d-1) intake allowed humans to maintain health, exercise, and physiologic function during 10 days of prolonged exercise-heat acclimation (HA). Seventeen volunteers, ages 19 to 21, consumed either LNA (n=8) or MNA (n=9) during HA (41°C, 21% RH; treadmill walking for 30 min.h-1, 8 h·d-1 at 5.6 kmh-l, 5% grade), which resulted in significantly reduced heart rate, rectal temperature, and urine Na+ for both groups. There were few between-diet differences in any variables measured. Mean plasma volume in LNA expanded significantly less than in MNA by Days 11 and 15, but reached the MNA level on Day 17 (+12.3 vs. +12.4%). The absence of heat illness, the presence of normal physiologic responses, and the total distance walked indicated successful and similar HA with both levels of dietary Na+.
Roy J. Shephard
Autonomic dysreflexia is a common response to painful stimuli following high level spinal injuries. Loss of normal control of sympathetic reflexes leads to large increases in blood pressure, accompanied by headache and occasional more dangerous sequelae. Although now officially banned, intentional dysreflexia ("boosting") is still exploited by some competitors to gain an unfair advantage. It is thus important to consider physiological mechanisms, consequences for health and performance, and methods of controlling this abuse. Boosters perceive the practice as frequent, performance enhancing, and of low immediate risk. Effective methods of eliminating the practice may include more stringent control of competitors, evaluating and publicizing short-and long-term risks, and countering arguments that boosting is an ethically acceptable method of restoring a normal physiological response.