Temporal Strength Changes From Resistance Exercise and Albuterol on Unloaded Muscle

Abstract

To assess unloaded knee extensor temporal strength changes, healthy subjects without asthma performed 40 continuous days of unilateral limb suspension, whereby their left leg refrained from normal weight-bearing and ambulatory activity. During the 40-day period, subjects performed resistance exercise (REX) with their unloaded leg on an inertial resistance ergometer and, as part of a double-blind design, consumed the maximal oral therapeutic dosage of albuterol (i.e., 16 mg.d) or a placebo (i.e., lactose) with no crossover. Workout data were partitioned into 4 10-day periods that ran consecutively. Dependent strength variables included concentric total work, eccentric total work, concentric average power (CAP), and eccentric average power (EAP). Dependent variables were analyzed with 5 (time) x 2 (group) x 2 (gender) mixed factorial analyses of variance and the Tukey honestly significant difference test. Concentric total work, CAP, and EAP each demonstrated a time-group-gender (p < 0.05) interaction. Female REX-placebo subjects had the greatest percentage of unloaded knee extensor strength loss. However, female REX-albuterol subjects fared best throughout the 40-day period and incurred significant unloaded knee extensor strength gains. Differences in strength changes between male and female REX-albuterol subjects was likely due to the higher relative dosage administered to the latter, as body mass showed a gender (i.e., men > women) effect. Future research may elucidate the ideal dose-response relationship for REX-albuterol treatment for use aboard manned space flights and in other disuse models. Coaches and practitioners should carefully examine their sport-governing bodies' rules on albuterol administration and give the drug only if an athlete's health warrants such treatment.

Hypertrophic effect of inhaled beta2‐agonist with and without concurrent exercise training: A randomized controlled trial

“…Le Panse et al did employ DXA scanning during 3‐4 weeks of oral salbutamol ingestion (12 mg/d), but employed a cross‐over design, which makes small changes in lean mass difficult to detect, as subjects who started with the salbutamol treatment most likely did not revert to baseline lean mass in the 4‐week washout period . In addition, studies that examined effects of salbutamol on body composition used self‐reported records as a measure of drug compliance, and lack of observed effects of salbutamol may therefore be attributed to low drug adherence. Indeed, studies show low drug compliance when relying on self‐reported records, being as low as 50% when the study drug is to be taken several times daily, as was the case for these studies .…”

“…In addition, studies that examined effects of salbutamol on body composition used self‐reported records as a measure of drug compliance, and lack of observed effects of salbutamol may therefore be attributed to low drug adherence. Indeed, studies show low drug compliance when relying on self‐reported records, being as low as 50% when the study drug is to be taken several times daily, as was the case for these studies . In addition, side effects associated with beta 2 ‐agonists may be unpleasant, and participants may deviate from the dosing regimen they were asked to follow .…”

“…It should be noted that in the present study, the hypertrophic effect of terbutaline was blunted when combined with non‐weight‐bearing exercise (ie, cycling), and whether this observation holds true for weight‐bearing exercise such as running is not known. When combined with resistance training, on the other hand, oral ingestion of salbutamol has been shown to enhance adaptations in muscle strength after limb unloading . In a recent study, Dickinson et al observed no additional effect of 6 weeks of daily inhalation of 400 μg salbutamol 4 times daily compared to placebo in training induced changes in muscle strength and skinfold thickness incurred from concurrent endurance and resistance training in young men.…”

Effect of beta2‐adrenergic agonist and resistance training on maximal oxygen uptake and muscle oxidative enzymes in men

“…Thus, beta 2 ‐adrenergic‐induced changes in O 2max and muscle oxidative enzymes may be confounded by particular types of training. Furthermore, in spite of the studies on the beta 2 ‐adrenergic effects on muscle strength in response to resistance training, no studies have, to our best knowledge, investigated whether concurrent resistance training affects adaptations in absolute and relative O 2max as well as in muscle oxidative enzymes in response to chronic beta 2 ‐adrenergic agonist treatment. As such, while absolute O 2max may be unaltered by chronic beta 2 ‐adrenergic agonist treatment, their hypertrophic effect may compromise O 2max relative to body mass or lean mass.…”

Effects of Terbutaline Sulfate on Physiological and Biomechanical as Well as Perceived Exertion in Healthy Active Athletes: A Pilot Study

“…Thus, the present study also showed a significant main effect of gender in aerobic performance, with lower estimated VO 2max values in active female than male athletes after the MFST. In contrast, during supra‐maximal exercise after salbutamol intake (3‐4 weeks, 12 mg daily), some studies showed no potentiating effects of gender (Caruso et al, 2008; Le Panse et al, 2005). In addition, no significant differences were observed between males and females in both groups for RPE value in the current study.…”