This study examined the effect of magnesium supplementation on muscle magnesium content, on running performance during a 42-kni marathon footrace, and on muscle damage and the rate of recovery of muscle function following the race. Twenty athletes were divided equally into two matched groups and were studied for 4 weeks before and 6 weeks after a marathon in a double-blind trial; the experimental group received magnesium supplement (365 mg per day) and the control group, placebo. Magnesium supplementation did not increase either muscle or serum magnesium concentrations and had no measurable effect on 42-km marathon running performance. Extra magnesium ingestion also had no influence on the extent of muscle damage or the rate of recovery of muscle function. The latter was significantly reduced immediately after the marathon but returned to normal within 1 week. Thus, magnesium supplementation in magnesium-replete subjects did not enhance performance or increase resistance to muscle damage during the race, or the rate of recovery of muscle function following the race.
Sonja Terblanche, Timothy D. Noakes, Steven C. Dennis, De Wet Marais and Michael Eckert
Kazunori Nosaka and Priscilla M. Clarkson
This study was done to determine whether eccentric exercise that causes muscle damage will produce an increase in plasma levels of zinc. Changes in total plasma zinc concentration (Zn) were examined following an eccentric and concentric exercise of the forearm flexors. Eight female subjects performed 24 maximal concentric actions (CON) with one arm and 10-14 days later performed 24 maximal eccentric actions (ECC) with the other arm. Maximal isometric force, elbow joint angles at a relaxed (RANG) and flexed position (FANG), muscle soreness, and plasma creatine kinase activity (CK) were measured as indicators of muscle damage. Zn levels were determined at the same time as CK. Maximal isometric force, RANG, FANG, and muscle soreness showed large changes after ECC but little if any change after CON. CK increased significantly after ECC but did not change after CON. Neither ECC nor CON showed significant changes in Zn following exercise. If: is concluded that exercise-induced muscle damage does not appear to produce an increase in plasma zinc levels.
Thomas M. Doering, Peter R. Reaburn, Stuart M. Phillips and David G. Jenkins
Participation rates of masters athletes in endurance events such as long-distance triathlon and running continue to increase. Given the physical and metabolic demands of endurance training, recovery practices influence the quality of successive training sessions and, consequently, adaptations to training. Research has suggested that, after muscle-damaging endurance exercise, masters athletes experience slower recovery rates in comparison with younger, similarly trained athletes. Given that these discrepancies in recovery rates are not observed after non–muscle-damaging exercise, it is suggested that masters athletes have impairments of the protein remodeling mechanisms within skeletal muscle. The importance of postexercise protein feeding for endurance athletes is increasingly being acknowledged, and its role in creating a positive net muscle protein balance postexercise is well known. The potential benefits of postexercise protein feeding include elevating muscle protein synthesis and satellite cell activity for muscle repair and remodeling, as well as facilitating muscle glycogen resynthesis. Despite extensive investigation into age-related anabolic resistance in sedentary aging populations, little is known about how anabolic resistance affects postexercise muscle protein synthesis and thus muscle remodeling in aging athletes. Despite evidence suggesting that physical training can attenuate but not eliminate age-related anabolic resistance, masters athletes are currently recommended to consume the same postexercise dietary protein dose (approximately 20 g or 0.25 g/kg/meal) as younger athletes. Given the slower recovery rates of masters athletes after muscle-damaging exercise, which may be due to impaired muscle remodeling mechanisms, masters athletes may benefit from higher doses of postexercise dietary protein, with particular attention directed to the leucine content of the postexercise bolus.
Ian M. Wilcock, John B. Cronin and Wayne A. Hing
To assess the effect that post exercise immersion in water has on subsequent exercise performance.
A literary search and review of water-immersion and performance studies was conducted.
Seven articles were examined. In 2, significant benefits to performance were observed. Those 2 articles revealed a small to large effect on jump performance and isometric strength.
Practical Application and Conclusions:
It is possible that water immersion might improve recovery from plyometric or muscle-damaging exercise. Such a statement needs to be verified, however, because of the scarcity of research on water immersion as a recovery strategy.
Gary Slater, David Jenkins, Peter Logan, Hamilton Lee, Matthew Vukovich, John A. Rathmacher and Allan G. Hahn
This investigation evaluated the effects of oral β-Hydroxy-β-Methylbutyrate (HMB) supplementation on training responses in resistance-trained male athletes who were randomly administered HMB in standard encapsulation (SH), HMB in time release capsule (TRH), or placebo (P) in a double-blind fashion. Subjects ingested 3 g · day−1 of HMB or placebo for 6 weeks. Tests were conducted pre-supplementation and following 3 and 6 weeks of supplementation. The testing battery assessed body mass, body composition (using dual energy x-ray absorptiometry), and 3-repetition maximum isoinertial strength, plus biochemical parameters, including markers of muscle damage and muscle protein turnover. While the training and dietary intervention of the investigation resulted in significant strength gains (p < .001) and an increase in total lean mass (p = .01), HMB administration had no influence on these variables. Likewise, biochemical markers of muscle protein turnover and muscle damage were also unaffected by HMB supplementation. The data indicate that 6 weeks of HMB supplementation in either SH or TRH form does not influence changes in strength and body composition in response to resistance training in strength-trained athletes.
Renee A. Dalton, Janet Walberg Rankin, Don Sebolt and Frank Gwazdauskas
The effect of acute carbohydrate consumption on performance and metabolism of resistance-trained males was determined. Twenty-two subjects, assigned to either carbohydrate (C, n = 8), placebo (P, n - 8), or control (N, n = 6), performed standardized workouts every other day for a week prior to testing and throughout the testing period. Three of these workouts (Tl, T2, and T3) were the performance test in that the last bouts of leg extension and bench press were done to failure at 80% of 10 repetition maximum. A carbohydrate or placebo beverage was consumed 30 min prior to T3. Blood samples were drawn before and after T2 and T3. There was no effect of carbohydrate or energy restriction on number of repetitions done during the leg extension performance test. Carbohydrate intake prior to a resistance exercise bout done in negative energy balance state did not affect performance or evidence of muscle damage.
Mitchell M. Kanter
Free radicals have been implicated in the development of diverse diseases such as cancer, diabetes, and cataracts, and recent epidemic-logical data suggest an inverse relationship between antioxidant intake and cardiovascular disease risk. Data also suggest that antioxidants may delay aging, Research has indicated that free radical production and subsequent lipid peroxidation are normal sequelae to the rise in oxygen consumption with exercise. Consequently, antioxidant supplementation may detoxify the peroxides produced during exercise and diminish muscle damage and soreness. Vitamin E, beta carotene, and vitamin C have shown promise as protective antioxidants. Other ingestible products with antioxidant properties include selenium and coenzyme
Ewa Jówko, Jaroslaw Sacharuk, Bozena Balasinska, Jacek Wilczak, Malgorzata Charmas, Piotr Ostaszewski and Robert Charmas
To evaluate the effect of acute ingestion of green tea polyphenols (GTP) on blood markers of oxidative stress and muscle damage in soccer players exposed to intense exercise.
This randomized, double-blinded study was conducted on 16 players during a general preparation period, when all athletes participated in a strength-training program focused on the development of strength endurance. After ingestion of a single dose of GTP (640 mg) or placebo, all athletes performed an intense muscle-endurance test consisting of 3 sets of 2 strength exercises (bench press, back squat) performed to exhaustion, with a load at 60% 1-repetition maximum and 1-min rests between sets. Blood samples were collected preexercise, 5 min after the muscle-endurance test, and after 24 hr of recovery. Blood plasma was analyzed for the concentrations of thiobarbituric acid–reacting substances (TBARS), uric acid (UA), total catechins, total antioxidant status (TAS), and activity of creatine kinase (CK); at the same time, erythrocytes were assayed for the activity of superoxide dismutase (SOD).
In both groups, plasma TBARS, UA, and TAS increased significantly postexercise and remained elevated after a 24-hr recovery period. SOD activity in erythrocytes did not change significantly in response to the muscle-endurance test, whereas in both groups plasma CK activity increased significantly after 24 hr of recovery. Acute intake of GTP cased a slight but significant increase in total plasma catechins. However, GTP was found not to exert a significant effect on measured parameters.
Acute ingestion of GTP (640 mg) does not attenuate exercise-induced oxidative stress and muscle damage.
Rebecca A. Skillen, Massimo Testa, Elizabeth A. Applegate, Eric A. Heiden, Andrea J. Fascetti and Gretchen A. Casazza
This study examined the effect of amino acids in a carbohydrate beverage on cycling performance. Twelve male athletes (28.5 pp2.1 yr) cycled at 75% VO2peak for 90 min followed by a ride to exhaustion at 85% VO2peak, before (T1) and on 2 consecutive days (T2 and T3) after 2 weeks of supplementation with 3.6% carbohydrate plus 1% amino acids (AA) or 4.6% carbohydrate-only (CHO) isocaloric beverages. Muscle damage was assessed by plasma creatine kinase (CK), and muscle fatigue by changes in vertical jump pre- to postexercise. Muscle soreness, overall fatigue, and changes in mood state were assessed using questionnaires. Plasma CK was lower for AA in T3 (214.0 ss13.5 vs. 485.9 11191.4 U/L immediately post, 213.9 ÷ 13.1 vs. 492.0 ÷ 199.4 U/L 5 hr post, and 194.9 ÷ 17.9 vs. 405.9 ÷ 166.6 U/L 24 hr postexercise in AA and CHO, respectively). Time to exhaustion decreased from T2 to T3 only in CHO (10.9 ÷ 2.5 to 12.6 ÷ 3.2 vs. 13.8 ÷ 2.8 to 7.8 ÷ 1.5 min in AA and CHO, respectively). Vertical-jump change from pre- to postexercise was greater in T3 for the CHO treatment. Total fatigue score and mood disturbance decreased significantly only with AA in T3. The addition of AA to a carbohydrate beverage after consecutive-day exercise bouts reduced muscle damage as indicated by CK levels, decreased fatigue, and maintained exercise performance compared with consuming carbohydrate alone.
Levent Cavas and Leman Tarhan
The relationship among the enzyme activities of cardiac markers, the antioxidant defense system, and erythrocyte membrane malonyldialdehyde (MDA) levels related to vitamin-mineral supplementation in swim exercise was investigated. Swimmers aged 11–13 years were divided into 2 separate groups as control and vitamin-mineral supplemented. Swimmers participated in a monthly swimming program (4 times/wk) and swam approximately 2–2.5 km/d. Cardiac markers such as creatine kinase (CK), creatine kinase-MB (CK-MB), glutamic oxaloacetic transaminase [GOT (AST)], lactate dehydrogenase (LDH), and antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities in post-training samples were found to be significantly (p < .05) higher than in pre-training samples. Except for GOT (AST), the activity increases in CK, CK-MB, and LDH in female and male supplemented groups were significantly (p < .05) lower than those of control groups during the 1-month period of swim training. Antioxidant enzyme activity increases in the male vitamin-mineral group were significantly (p < .05) higher when compared with the other groups. Post-training MDA levels were significantly (p < .001) higher than pre-training MDA levels in the control groups, whereas no significant (p > .05) differences were found between the vitamin-mineral supplemented groups. Vitamin-mineral supplementation was found to attenuate cardiac and muscle damage markers while also enhancing antioxidant levels and reducing membrane LPO levels in response to 1 month of swim training.