J. Stray-Gundersen

Motivation, overtraining, and burnout: Can self-determined motivation predict overtraining and burnout in elite athletes?

Abstract The aim of this study was to determine whether quality of self-determined motivation at the start of the competitive season in elite athletes and symptoms of overtraining can predict athlete burnout propensity at the end of the season. The participants were 141 elite winter sport athletes. In September, at the beginning of the season, the athletes responded to a self-determined motivation questionnaire, while they answered questions assessing overtraining symptoms and burnout in March, at the end of the season. Findings indicated that self-determined motivation and symptoms of overtraining were negatively and positively linked respectively to dimensions of athlete burnout. The results suggest that self-determined motivation and symptoms of overtraining are both independently linked to signs of burnout in elite athletes and that although no moderating effect was found, pairing self-determined motivation with symptoms of overtraining increased the prediction of burnout in athletes at the end of the season. Our findings are in line with those of recent research (Cresswell & Eklund, 2005; Lemyre, Treasure, & Roberts, 2006) and support a motivational approach to study burnout in elite athletes.

Exercise economy does not change after acclimatization to moderate to very high altitude

For more than 60 years, muscle mechanical efficiency has been thought to remain unchanged with acclimatization to high altitude. However, recent work has suggested that muscle mechanical efficiency may in fact be improved upon return from prolonged exposure to high altitude. The purpose of the present work is to resolve this apparent conflict in the literature. In a collaboration between four research centers, we have included data from independent high‐altitude studies performed at varying altitudes and including a total of 153 subjects ranging from sea‐level (SL) residents to high‐altitude natives, and from sedentary to world‐class athletes. In study A (n=109), living for 20–22 h/day at 2500 m combined with training between 1250 and 2800 m caused no differences in running economy at fixed speeds despite low typical error measurements. In study B, SL residents (n=8) sojourning for 8 weeks at 4100 m and residents native to this altitude (n=7) performed cycle ergometer exercise in ambient air and in acute normoxia. Muscle oxygen uptake and mechanical efficiency were unchanged between SL and acclimatization and between the two groups. In study C (n=20), during 21 days of exposure to 4300 m altitude, no changes in systemic or leg VO2 were found during cycle ergometer exercise. However, at the substantially higher altitude of 5260 m decreases in submaximal VO2 were found in nine subjects with acute hypoxic exposure, as well as after 9 weeks of acclimatization. As VO2 was already reduced in acute hypoxia this suggests, at least in this condition, that the reduction is not related to anatomical or physiological adaptations to high altitude but to oxygen lack because of severe hypoxia altering substrate utilization. In conclusion, results from several, independent investigations indicate that exercise economy remains unchanged after acclimatization to high altitude.

Live high, train low at natural altitude

For decades altitude training has been used by endurance athletes and coaches to enhance sea‐level performance. Whether altitude training does, in fact, enhance sea level performance and, if so, by what means has been the subject of a number of investigations. Data produced principally by Levine and Stray‐Gundersen have shown that living for 4 weeks at 2500 m, while performing the more intense training sessions near sea level will provide an average improvement in sea level endurance performance (duration of competition: 7–20 min) of approximately 1.5%, ranging from no improvement to 6% improvement. This benefit lasts for at least 3 weeks on return to sea level. Two mechanisms have been shown to be associated with improvement in performance. One is an increase in red cell mass (∼8%) that results in an improved maximal oxygen uptake (∼5%). That must be combined with maintenance of training velocities and oxygen flux to realize the improvement in subsequent sea level performance. We find no evidence of changes in running economy or markers of anaerobic energy utilization. Our results have been obtained in runners ranging from collegiate to elite. Wehrlin et al. have recently confirmed these results in elite orienteers. While there are no specific studies addressing the use of living high, training low in football players, it is likely that an improvement in maximal oxygen uptake, all other factors equal, would enhance football performance. This benefit must be weighed against the time away (4 weeks) from home and competition necessary to gain these benefits.

Capillarity of elite cross‐country skiers: a lectin (Ulex europaeus I) marker

Capillary morphometrics in human skeletal muscle has been limited by technical problems in visualization. The purpose of this study was to develop a method for identifying capillary endothelium at the light level of resolution and to reassess the skeletal muscle capillarity in trained and untrained subjects. A lectin system of biotinylated Ulex europaeus I (UEA‐I), a vascular endothelial marker, provided a stain dense enough for direct computer‐aided image analysis. A morphometric comparison was made between Andersens periodic acid‐Schiff and the UEA‐I capillary stains on tissue sections of human skeletal muscle. When identical fibers from adjacent sections were compared, the capillary density was 6% and cap fiber was 9% greater using the lectin method. Biopsies from 17 cross‐country skiers were compared with those of 8 age‐matched sedentary controls. The capillary density in the triceps muscle for the skiers was 536.1 ± 33.1 compared with 296 ± 17.7 for the controls. Longitudinal profiles that appear in skeletal muscle cross‐sections suggest a more isotropic (random orientation) configuration of the capillary bed than proposed by the Krogh model. There were 50.6% more longitudinal profiles in the trained samples. The UEA‐I lectin appears to be a valid and potentially useful marker for computerized image analysis of non‐pathological vascular endothelium, and the differences in capillarity between trained and untrained individuals may be greater than previously reported.

Effect of Intermittent Hypobaric Hypoxia on Erythropoiesis

We examined the effect of 3 hours of intermittent hypobaric hypoxia on erythropoiesis. METHODS: 23 trained athletes were randomly assigned to either hypobaric hypoxia (HYPO; simulated altitude of 4000-5500m) or normoxia (NORM; 0-500m) in a double-blind, placebo controlled design. Both groups rested in a hypobaric chamber for 3 h/day, 5 day/wk, for 4 wks. Total Hb mass (CO rebreathing) was measured twice before and twice after treatment. Blood was drawn 8 times during the 10-wk study, (twice before, once per week during and twice after) and analyzed for [Hb], reticulocyte Hb, soluble transferin receptor (sTfr) and erythropoietin (EPO). Blood was also drawn twice (Wk 2, Wk 4) within 3hrs of chamber exposure and assayed for EPO.

Hemodynamic Responses to Intermittent Hypoxia Exposure in Trained Athletes

1UNTHSC-Texas College of Osteopathic Medicine, Fort Worth, TX. 2Australian Institute of Sport, Canberra, Australia. 3Institute for Exercise and Environmental Medicine, Presbyterian Hospital/UT Southwestern Medical Center, Dallas, TX, Dallas, TX. 4Universtitat de Barcelona, Barcelona, Spain. 5Vrije Universteit Amsterdam, Amsterdam, Netherlands. 6Institute for Exercise and Environmental Medicine, Presebyterian Hospital/UT Southwestern Medical Center, Dallas, TX, Dallas, TX.

“Living high − training low” altitude training improves sea level performance in male and female élite runners

Acclimatization to moderate high altitude accompanied by training at low altitude (living high–training low) has been shown to improve sea level endurance performance in accomplished, but not élite, runners. Whether élite athletes, who may be closer to the maximal structural and functional adaptive capacity of the respiratory (i.e. oxygen transport from environment to mitochondria) system, may achieve similar performance gains is unclear. To answer this question, we studied 14 élite men and eight élite women before and after 27 days of living at 2500 m while performing high‐intensity training at 1250 m. The altitude sojourn began 1 week after the USA Track and Field National Championships, when the athletes were close to their seasons fitness peak. Sea level 3000‐m time trial performance was significantly improved by 1.1% (95% confidence limits 0.3–1.9%). One‐third of the athletes achieved personal best times for the distance after the altitude training camp. The improvement in running performance was accompanied by a 3% improvement in maximal oxygen uptake (72.1 ± 1.5–74.4 ± 1.5 ml kg− 1 min− 1). Circulating erythropoietin levels were near double initial sea level values 20 h after ascent (8.5 ± 0.5–16.2 ± 1.0 IU ml−1). Soluble transferrin receptor levels were significantly elevated on the 19th day at altitude, confirming a stimulation of erythropoiesis (2.1 ± 0.7–2.5 ± 0.6 μ g ml‐1). Hb concentration measured at sea level increased 1 g dl−1 over the course of the camp (13.3 ± 0.2–14.3 ± 0.2 g dl−1). We conclude that 4 weeks of acclimatization to moderate altitude, accompanied by high‐intensity training at low altitude, improves sea level endurance performance even in élite runners. Both the mechanism and magnitude of the effect appear similar to that observed in less accomplished runners, even for athletes who may have achieved near maximal oxygen transport capacity for humans.