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).
William M. Bertucci, Andrew C. Betik, Sebastien Duc and Frederic Grappe
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+.
Thomas W. Rowland
Performance in all forms of motor activity related to sport performance improves progressively during the course of the childhood years as a consequence of normal growth and development. Whether (a) sport training can accelerate and ultimately enhance this biological development and (b) the existence of certain ages when training might prove to be more effective in improving performance, particularly early in childhood, remains uncertain. Physiological adaptations to endurance training in prepubertal children (improvements in maximal oxygen uptake) are dampened compared with adults, but enhancements of strength following resistance training are equally effective at all ages. The extent that intensive training regimens characteristic of early sport specialization in children can trigger physiological and performance adaptations may therefore depend on the form of exercise involved. Clearly, additional research is needed to enhance the understanding of the physiological responses to intensive sport training in prepubertal individuals.
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%
Interest in the physiological responses to exercise unique to the pediatric age group has grown exponentially over the past 50 years. A number of issues surrounding children’s exercise have been particularly responsible for this trend, particularly a) recognition of the health benefits of exercise in youth, b) the growing involvement of young persons in highly intense levels of sports play, and c) the role that exercise may play in the diagnosis and management of children with chronic disease. As a consequence, current research to date has provided a comprehensive picture of the features specific to children’s response to exercise. Future challenges facing the field of pediatric exercise science involve translating this information into practical guidelines which can be applied to the realms of clinical medical practice, preventive health initiatives, and athletic training regimens which are appropriate for this age group.
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.
Peter J. Lang
Emotions are organized around 2 basic motivational systems, appetitive and defensive, that evolved from primitive neural circuits in the mammalian brain. The appetitive system is keyed for approach behavior, founded on the preservative, sexual, and nurturant reflexes that underlie pleasant affects; the defense system is keyed for withdrawal, founded on protective and escape reflexes that underlie unpleasant affects. Both systems control attentional processing: Distal engagement by motive-relevant cues prompts immobility and orienting. With greater cue proximity (e.g., predator or prey imminence), neural motor centers supercede, determining overt defensive or consummatory action. In humans, these systems determine affective expression, evaluation behavior, and physiological responses that can be related to specific functional changes in the brain. This theoretical approach is illustrated with psychophysiological and brain imagery studies in which human subjects respond to emotional picture stimuli.
Sarah E. Williams, Jennifer Cumming and George M. Balanos
The present study investigated whether imagery could manipulate athletes’ appraisal of stress-evoking situations (i.e., challenge or threat) and whether psychological and cardiovascular responses and interpretations varied according to cognitive appraisal of three imagery scripts: challenge, neutral, and threat. Twenty athletes (M age = 20.85; SD = 1.76; 10 female, 10 male) imaged each script while heart rate, stroke volume, and cardiac output were obtained using Doppler echocardiography. State anxiety and self-confidence were assessed following each script using the Immediate Anxiety Measures Scale. During the imagery, a significant increase in heart rate, stroke volume, and cardiac output occurred for the challenge and threat scripts (p < .05). Although there were no differences in physiological response intensities for both stress-evoking scripts, these responses, along with anxiety symptoms, were interpreted as facilitative during the challenge script and debilitative during the threat script. Results support using imagery to facilitate adaptive stress appraisal.
Kamuran Yerlikaya Balyan, Serdar Tok, Arkun Tatar, Erdal Binboga and Melih Balyan
The present study examined the association between personality, competitive anxiety, somatic anxiety and physiological arousal in athletes with high and low anxiety levels. Anxiety was manipulated by means of an incentive. Fifty male participants, first, completed the Five Factor Personality Inventory and their resting electro dermal activity (EDA) was recorded. In the second stage, participants were randomly assigned to high or low anxiety groups. Individual EDAs were recorded again to determine precompetition physiological arousal. Participants also completed the Competitive State Anxiety Inventory-2 (CSAI-2) and played a computer-simulated soccer match. Results showed that neuroticism was related to both CSAI-2 components and physiological arousal only in the group receiving the incentive. Winners had higher levels of cognitive anxiety and lower levels of physiological arousal than losers. On the basis of these findings, we concluded that an athlete’s neurotic personality may influence his cognitive and physiological responses in a competition.
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.