The effects of two weeks of recombinant growth hormone administration on the response of IGF-I and N-terminal pro-peptide of collagen type III (P-III-NP) during a single bout of high resistance exercise in resistance trained young men

ObjectiveRecombinant human growth hormone (rhGH) is used by some athletes and body builders with the aim of enhancing performance, building muscle and improving physique. Detection of the misuse of rhGH has proved difficult for a number of reasons. One of these is the effect of preceding exercise. In this randomised, double blind placebo-controlled study, we determined the effects of rhGH administration in male amateur athletes on two candidate markers of rhGH abuse, IGF-I and N-terminal pro-peptide of collagen type III (P-III-NP), following a bout of weightlifting exercise.DesignSixteen men entered a four-week general weight training programme to homogenise their activity profile. They then undertook repeated bouts of standardised leg press weightlifting exercise (AHRET-acute heavy resistance exercise test). Blood samples were taken before and up to one hour after the AHRET. After the first laboratory visit (Test 1), the subjects were randomly assigned to receive daily injections of either rhGH (0.1 IU kg^? 1 day^? 1) or placebo for two weeks. The AHRET was repeated after the two-week dosing period (Test 2) and a further test was undertaken following a one-week washout (Test 3).ResultsThere was no effect of exercise on either IGF-I or P-III-NP in any test. Both markers were markedly elevated at Test 2 (p < 0.001), with P-III-NP remaining elevated at Test 3 in the GH administration group (p < 0.05). Application of the GH-2000 discriminant function positively identified GH administration in 17 of 40 blood samples taken at Test 2 from the rhGH group and none from the placebo group.ConclusionThe data show that rhGH results in elevated levels of IGF-I and P-III-NP in well-trained individuals and that leg press weightlifting exercise does not affect these markers. The GH-2000 discriminant function identified four of eight subjects taking rhGH with no false positive results.     

Dietary regimen and performance of high intensity ergometer exercise.

The influence of preceding diet (mixed, MD; carbohydrate CD; protein PD) on performance during high intensity endurance cycling was examined in six middle distance runners. Subjects undertook cycle ergometer exercise at a workload equivalent to 80% VO2 max until exhaustion following each of the three dietary regimens. Dietary analyses were performed using a computerised evaluation technique and cardiorespiratory, blood glucose and lactate responses to exercise were measured along with exercise time to exhaustion. Significant differences in carbohydrate and protein intakes were noted between respective diets as well as significantly higher total energy intake in MD (P less than 0.05). A significant relationship was observed between carbohydrate intake and exercise time to exhaustion (r = 0.59, P less than 0.05). No significant differences were noted in cardiorespiratory measures or blood glucose response after exhaustive exercise between the three dietary regimens but peak blood lactate concentration was lower following PD (P less than 0.05). Total time to exhaustion was significantly higher on CD (1070.0 +/- 106.7 s) than on PD (642.5 +/- 84.3 s, P less than 0.01). Performance time on MD (895.7 +/- 84.3 s) did not differ significantly for performance time on either CD or PD. It was concluded that dietary manipulation significantly improves exercise time to exhaustion during short term, high intensity cycling.     

Insulin-like growth factor-1 gene splice variants as markers of muscle damage in levator ani muscle after the first vaginal delivery

OBJECTIVE: Studies in animals and human muscle have demonstrated differential splicing of the insulin-like growth factor-1 gene in response to mechanical strain and damage. We conducted a study on the expression of insulin-like growth factor-1 splice variants in the levator ani muscle after the first vaginal delivery. STUDY DESIGN: Ten women were recruited after the first vaginal delivery. Biopsy specimens were taken vaginally of the pubovisceral component of the levator ani muscle. Five nonpregnant women were recruited as control subjects. Samples were processed with real-time quantitative polymerase chain reaction, with specific primers for the insulin-like growth factor-1 splice variants. RESULTS: Insulin-like growth factor splice variants mechano growth factor and insulin-like growth factor-1Ea were significantly up-regulated (100- and 1000-fold) in the delivery population, compared with control subjects (P=.012 and .04, respectively). Statistical analysis indicated a correlation between the expression of the insulin-like growth factor-1 splice variants and the length of the second stage. CONCLUSION: These results show that damaged levator ani muscle results from stretch and overload after the first vaginal delivery.     

Effects of endurance and strength-directed electrical stimulation training on the performance and histological properties of paralyzed human muscle: a pilot study

Electrical stimulation (ES) improves muscle properties after spinal cord injury (SCI), but cycling power output (PO) remains low. We investigated the effect of endurance and strength ES training on these parameters. Assessments of quadriceps strength and fatigue resistance, cycling PO, and muscle biopsies were made in four well-trained SCI subjects (three cyclists and one rower) before and after additional weight training in the cyclists and once in the rower. Weight training improved muscle strength, but cycling PO was low in all subjects. There was no effect of training type on biopsy data. Biopsies showed non-specific signs of pathology, predominance of type IIa fibers, and uniform metabolic activity. Oxidative activity was low, as were capillary:fiber ratios in the cyclists. Cycling PO is limited by factors other than muscle strength. Future ES training studies should attempt to improve muscle oxidative capacity to optimize the potential benefits of ES exercise.