Reversed drift in heart rate but increased oxygen uptake at fixed work rate during 24 h ultra-endurance exercise.

In this paper we report a reversed drift in heart rate (HR) but increased oxygen uptake (VO(2)) during ultra-endurance exercise. Nine well-trained male athletes performed 24-h exercise in a controlled laboratory setting, with alternating blocks of kayaking, running and cycling. Each block included 110 min of exercise and 10 min of rest, with an average work intensity of approximately 55% of respective VO(2peak). Blood samples were taken and HR and VO(2) measured every 6th hour during steady-state cycling at fixed work rate. As assumed HR was increased at 6 h by 15 +/- 6 beats/min compared with initial level (0 h). Thereafter the drift did not progress continuously, but instead unexpectedly returned toward initial values, although the plasma levels of catecholamines increased continuously during exercise. VO(2) was increased by 0.22 +/- 0.15 L/min (10%) at 6 h and 0.37 +/- 0.18 L/min (17%) at 12 h compared with 0 h, and thereafter remained stable. This implies an increased oxygen pulse (VO(2)/HR) by approximately 10% at the last half of the 24-h exercise compared with 0 h. Consequently, sole use of HR would give inaccurate estimates of exercise intensity and energy expenditure during endurance exercise lasting more than 6 h, and different patterns of cardiovascular drift need to be taken into account.

Lack of sex differences in the IGF-IGFBP response to ultra endurance exercise.

The insulin-like growth factor (IGF)-IGF binding proteins (BP) and the pituitary-gonadal axes were investigated during ultra endurance exercise in 16 endurance-trained athletes (seven women). Median duration of the race was 6.3 days. Although food and drink were ad libitum, energy balance was negative. Blood samples were drawn before (PRE), at the end of (END) and 24 h after (POST24h) the race. Serum concentrations of total IGF-I (t-IGF-I) and free IGF-I (f-IGF-I) decreased by 33 (SD 38)% and 54 (19)%, respectively. The decrease in t-IGF-I appeared to be associated to the total energy deficit during the race. At END, the IGFBP-3 fragmentation and IGFBP-1 were increased but these changes did not predict changes in f-IGF-I. An increase in POST24h IGFBP-2 levels in women was the only sex difference. Testosterone was decreased by 67 (12)% in the men and estradiol became undetectable in the women without any detectable increase in LH and/or FSH. In conclusion ultra endurance exercise results in similar IGF-IGFBP responses in men and women reflecting a catabolic state. IGFBP-2 was the only exception, with increased levels in women after exercise. A concomitant decrease in gonadal hormones was not related to endocrine changes in the IGF-IGFBP axis but may be related to local changes in IGF-I expression.

Evaluation of a language-screening programme for 2.5-year-olds at Child Health Centres in Sweden.

UNLABELLED: A population-based language-screening programme started in the western part of Sweden (South Bohuslän) in 1991, with the aim of identifying developmental language disability in 2.5-y-old children. The programme was evaluated during 1998 in an experimental study. A group of 105 2.5-y-old children was recruited from 24 separate Child Health Centres. A sample of 25 children with a positive screening result was selected. For each of the 25 children, 1-4 controls, i.e. children with a negative screening result, were selected. The results were reclassified blindly by three speech and language therapists and used as a gold standard. Positive and negative predictive values were estimated to be 0.52 (95% confidence interval 0.31-0.72) and 0.96 (95% confidence interval 0.89-0.99), respectively. Baye's theorem was used to calculate the sensitivity (0.69) and the specificity (0.93) of the screening. A method of calculating the sensitivity and specificity of the test method by means of three samples was demonstrated. CONCLUSION: The data confirm that it is possible to identify reliably children with developmental language disability at 2.5 y of age through the screening programme.