Summary Nine Thoroughbred horses were assessed to determine the normal response of insulin, glucose, Cortisol, plasma potassium (K) and erythrocyte K through conditioning and to exercise over 400 and 1,000 m. In addition, adrenaline, noradrenaline, Cortisol, plasma K, erythrocyte K and L‐lactate concentrations were evaluated in response to maximal exercise with and without the administration of acepromazine. Conditioning caused no obvious trends in plasma K, erythrocyte K, insulin or glucose concentration. Serum Cortisol increased (P < 0.05) from the initial sample at Week 1 to Weeks 4 and 5 (attributed to a response to training), and then decreased. During conditioning, three horses had low erythrocyte K concentrations (< 89.3 mmol/litre). Further work is needed to define the significance of low erythrocyte K concentrations in the performance horse. In all tests maximal exercise increased plasma K, glucose and Cortisol concentrations, whereas insulin and erythrocyte K concentrations decreased. Thirty minutes following exercise, plasma K and erythrocyte K concentrations returned to resting values, whereas glucose and Cortisol concentrations continued to increase and the insulin concentration also was increased. The magnitude of the changes varied for pre‐conditioned vs post‐conditioned exercise tests and the duration of exercise. The administration of acepromazine prior to exercise over 1,000 m failed to alter the circulating noradrenaline and adrenaline concentrations in anticipation of exercise or 2 mins following exercise. Acepromazine administration, however, did cause lower L‐lactate concentration 2 mins (P < 0.03) and 30 mins (P ≤ 0.005) following exercise. Also, erythrocyte K showed a delayed return to baseline levels at 30 mins post exercise. Further evaluation of these trends may help explain the beneficial role acepromazine plays in limiting signs of exertional rhabdomyolysis when administered prior to exercise.

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Regular physical activity influences plasma ghrelin concentrations in girls with different pubertal maturation levels. Plasma IGF-I concentration seems to be the main determinant of circulating ghrelin in healthy, normal-weight adolescent girls.

The purpose of the present study was to investigate the use of electromyographic signals (EMG), to determine the EMG threshold (EMGT) in four lower extremity muscles and to compare these thresholds with the second ventilatory threshold (VT2) in subjects participating in different sports and at different performance levels. Forty-nine subjects (23.8 +/- 5.7 years, 182.7 +/- 5.3 cm, 79.1 +/- 8.6 kg) including eleven cyclists, ten team-handball players, nine kayakers, eight power lifters and eleven controls were investigated utilizing a cycle ergometer. Respiratory gas exchange measures were collected and EMG activity was continuously recorded from four muscles (vastus lateralis, vastus medialis, biceps femoris and gastrocnemius lateralis). The VO(2)max averaged 56.1 +/- 11.1 ml kg(-1) min(-1), the average aerobic power was 348.5 +/- 61.0 W and the corresponding VT2 occurred at 271.4 +/- 64.0 W. The EMGT ranged from 80 to 98% of power output for the different muscles. The VT2 and EMG thresholds from four different muscles were not different. When thresholds were analyzed among different groups of subjects, no significant difference was observed between VT2 and EMGT despite threshold differences between the groups. All four EMGT were significantly related to maximal aerobic power (r = 0.73-0.83) and were highly correlated to each other (r = 0.57-0.88). In conclusion, EMGT can be used to determine the VT2 for individuals independent of sport specificity or performance level.

Subcutaneous morphine inhibited lymphocyte proliferation, decreased splenic lymphocyte number, and altered phenotypic expression of cell surface markers, whereas equianalgesic doses of intrathecal morphine did not. Although these results suggest that spinal opioids may have theoretical benefits for the analgesic management of immunocompromised patients, further studies are clearly indicated.