Inspiratory muscle training in exercise-induced paradoxical vocal fold motion.

The purpose of the study was to determine if inspiratory muscle training (IMT) would result in increased inspiratory muscle strength, reduced perception of exertional dyspnea, and improved measures of maximal exercise effort in an athlete with exercise-induced paradoxical vocal fold motion (PVFM). The participant, an 18-year-old woman, had a 2-year history of acute dyspnea with exertion during soccer games. Spirometry, transnasal flexible laryngoscopy, and patient history supported a PVFM diagnosis. The ABAB within-subject withdrawal design study comprised IMT treatment and withdrawal phases, each lasting 5 weeks. The participant trained 5 days per week, completing five sets of 12 breaths at 75% maximum inspiratory pressure (MIP) per session. Data consisted of MIP, exertional dyspnea ratings, and maximal exercise measures. IMT resulted in increased MIP and decreased dyspnea ratings across both treatment phases. No change in MIP or dyspnea ratings occurred in response to treatment withdrawal. The maximal exercise test revealed minimal changes across phases. At end of the study, the participant reported experiencing no PVFM symptoms when performing the outcome measurement tasks and when playing soccer. Transnasal flexible laryngoscopy, after strenuous exercise and during rapid breathing and phonation tasks, revealed normal laryngeal findings. The findings suggest that IMT may be a promising treatment approach for athletes with exercise-induced PVFM.

Magnesium-creatine supplementation effects on body water.

This study evaluated magnesium-creatine (MgCre) supplementation on body water and quadriceps torque. Maltodextran (Placebo), Mg oxide plus Cre (MgO-Cre), and Mg-creatine chelate (MgC-Cre) at 800 mg Mg and 5 g Cre per day were used for 2 weeks in 35 subjects in a random assignment, blinded study. Pre-post measures were completed with bioimpedance to determine total body water (TBW), extracellular water (ECF), and intracellular water (ICF), and an isokinetic device at 180 degrees per second for knee extension peak torque (T), total work (W), and power (PWR). Body weights increased for both treatment groups, MgO-Cre Delta 0.75 kg (P <.05) and MgC-Cre Delta 0.4 kg (P =.07). Significant pre-post differences (P <.05) were noted only for MgC-Cre in ICW (26.29 v 28.01 L) and ECW (15.75 v 14.88 L). MgC-Cre had significant peak T (Nm) increase (124.5 v135.8, P <.05), while MgO-Cre (116.4 v 124.9, P =.06) and placebo (119.8 v 123.7, P =.343) did not. Both treatment groups had increased PWR (P <.05). MgC-Cre affects cellular fluid compartments. The peak torque changes were significant only in the MgC-Cre group, which had increases in ICW that may infer more muscular creatine due to its osmotic effect, and with increased cellular hydration, perhaps increased protein synthesis.

Effect of sonic driving on maximal aerobic performance.

The study purpose was to evaluate antecedent binaural stimulation (ABS) on maximal aerobic physical performance. Twenty-two healthy, physically active subjects, 21-34 years, randomly received one of two preparations for each session: 15 min of quiet (BLANK) or percussive sonic driving at 200+ beats per minute (bpm) using a recorded compact disc (FSS, Mill Valley, CA) with headphones (ABS). Baseline HR, blood pressure (BP), and breathing frequency (f(br)) were obtained. During each condition, HR and f(br) were recorded at 3-min intervals. The graded maximal treadmill testing was administered immediately postpreparation session on separate days, with at least 48 h rest between sessions. There were significant differences in the antecedent period means between the two conditions, ABS (HR: 70.2 +/- 10.7 bpm; f(br): 18.5 +/- 3.3 br min(-1); BP: 134.5/87.9 +/- 13.6/9.2 mm Hg) and BLANK (HR: 64.6 +/- 7.9; f(br): 14.3 +/- 2.9; BP: 126.7/80.3 +/- 12.1/8.6). Differences were noted for each 3-min interval and pre- postantecedent period. The maximal graded exercise test (GXT) results showed that there was a small but significant (P < 0.05), increase in maximal VO(2) in the ABS (49.8 +/- 6.8 ml. kg(-1). min(-1)) vs. BLANK (46.7 +/- 8.7) conditions. Related to that finding was a slight increase (0.5 min) in time to exhaustion (P < 0.05). There were no significant differences in HR or RPE (P > 0.05). There may be a latency to ABS related to entrainment or imagery-enhanced warm-up. Am. J. Hum. Biol. 12:558-565, 2000. Copyright 2000 Wiley-Liss, Inc.

Effect of strength training on orthostatic hypotension in older adults.

PURPOSE: This preliminary study attempted to identify the frequency of orthostatic hypotension (OH) in community dwelling older adults who volunteered to participate in an 8-week, heavy-resistance, strength-training program. It also assessed the effect of the strength-training program on OH. METHODS: From a larger study (n = 53) on high-resistance strength training in older adults (mean age 71.4 +/- 6.6 years), a subset of subjects (n = 24), mean age 71.0 +/- 5.8 years, was evaluated who met at least one criterion for OH. All subjects were tested for resting blood pressures (BP) and heart rates (HR) in the supine, sitting, and standing positions. Also noted was their response to orthostatism in rising from a cot after 10 minutes and rising from a chair after 5 minutes. The subset was not different from the overall group in gender ratio, age, or effect of medication on BP. The treatment was an 8-week strength-training program at 80% of their one repetition maximum. RESULTS: Significant changes (P < 0.05) were shown in supine diastolic BP (+3.2 mm Hg), sitting systolic BP (-3.9), and standing HR (+4.9 beats per minute). In response to the orthostatic challenge, significant (P < 0.05) improvements were shown in systolic BP (+9.7 mm Hg), diastolic BP (+4.7), and HR (+3.2 beats per minute) for the rise from chair, and in diastolic BP (+6.7 mm Hg) rise from the cot. CONCLUSIONS: These data show that OH is not uncommon (45%) in community dwelling older adults. A strength training program in older adults has little effect on resting BP, but elicits a positive adaptation to an orthostatic challenge.

Effect of magnesium supplementation on strength training in humans.

UNLABELLED: This study investigated the effects of dietary magnesium (Mg) on strength development during a double-blind, 7-week strength training program in 26 untrained subjects (14 = control, C and 12 = Mg supplemented, M), 18-30 years old. Subjects' 3-day diet records were analyzed and Mg content was calculated. C received a placebo and M received a supplement (Mg oxide) to bring Mg intake, including diet, to 8 mg/kg body weight/day. Body composition was assessed with bioelectrical impedance. Pre and post quadriceps torque (T) measurements were made with an Orthotron at 120 deg/sec. Each subject performed three sets of 10 reps, leg press and leg extension, three times/week. Both groups gained strength, however, results indicated a significant (p less than 0.05) increase for the M group compared to the C group in absolute T, relative T adjusted for body weight (T/BWT), and relative T adjusted for lean body mass (T/LBM) when pre values were used as the covariate. M was consistently greater than C (T: 211 vs 174 Nm; T/BWT: 3.07 vs 2.58 Nm/kg; T/LBM: 3.84 vs 3.36 Nm/kg). CONCLUSION: Significant differences in T gains after strength training were demonstrated in M vs C. Mg's role may be at the ribosomal level in protein synthesis.

Effect of fish oil supplementation and exercise on serum lipids and aerobic fitness.

The effects of fish oil supplementation and exercise were investigated in healthy, previously sedentary males, ages 19-34. Thirty-two subjects were assigned to four groups: control (C), fish (F), exercise (E), fish and exercise (FE). The fish groups consumed 4 g.d-1 of omega-3 fatty acids. The exercise groups performed aerobic exercise for one hour three per week. The study was conducted for 10 weeks with pre and post values obtained for cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol, maximal oxygen consumption (VO2max), ventilatory anaerobic threshold (VAT), percent body fat, and dietary composition of macronutrients and polyunsaturated to saturated fat (P:S) ratio. No significant differences were noted between groups for any of the blood lipid values, percent body fat or dietary variables. VO2max and VAT did exhibit significant changes among groups. VO2max was greater for the exercise groups (E, FE) as compared to the control group (p less than 0.05). E, but not FE, was significantly greater than F. VAT was significantly greater in F, E, and FE as compared to controls, however the control's VAT decreased slightly. The slight improvement, although statistically non-significant, in VO2max and VAT by the F group requires further study. This data indicates an improvement in aerobic metabolism from aerobic exercise, alone or in combination with fish oil, compared to controls.

Effect of hypomagnesemia and exercise on slowly exchanging pools of magnesium.

The effects of hypomagnesemia and exercise on the slowly exchanging pools of magnesium, skeletal muscle, bone, erythrocytes, and plasma, were examined in four groups of male Sprague-Dawley rats: sedentary-normal diet (SN), exercise-normal diet (EN), sedentary-hypomagnesemic diet (SH), and exercise-hypomagnesemic diet (EH). The exercise groups swam 5 d/wk-1 for 6 weeks. The hypomagnesemic diet contained 80 ppm and the normal diet about 640 ppm of magnesium. Compared with normal-diet rats (SN and EN), dietary-deficient rats (SH and EH) gained less weight and had lower concentrations of magnesium in all tissue samples and plasma (P less than .01). Exercise groups (EN and EH) demonstrated significantly higher magnesium levels in skeletal muscle (P less than .01) and a tendency for lower levels of magnesium in plasma, erythrocytes, and bone compared with sedentary groups (SN & SH). EH rats normalized skeletal muscle magnesium, mEq.kg-1 wet tissue, (19.9 +/- 5.1) compared with the SN group (20.6 +/- 2.1). Assuming that magnesium stores that are rapidly exchanged are maintained at the expense of those that are slowly exchanged, magnesium stores in skeletal muscle appear to be most protected, with the effect accentuated by exercise.

Variable response of serum magnesium and total cholesterol to different magnesium intakes and exercise levels in rats.

Thirty-two Sprague-Dawley rats were divided into four groups: control, exercise, low-magnesium diet, and a combination of low-magnesium diet and exercise. The low-magnesium diet contained 80 ppm of magnesium and the exercise consisted of 1-hour swim sessions, 5 days per week for 4 weeks. Serum magnesium was depressed and total cholesterol was elevated (p less than 0.05) in the low-magnesium diet, sedentary animals as compared to both sedentary and exercised rats fed a normal magnesium diet. The group on the combination of hypomagnesemic diet and exercise was not statistically different from the normal-diet group. It is concluded that exercise favorably affects the serum magnesium and cholesterol responses induced by a hypomagnesemic diet. There may be a threshold serum magnesium level to elicit the elevated cholesterol response, or other metabolic factors affected by exercise may modify the expected cholesterol response associated with deprivation or severe deficiency of dietary magnesium and related serum magnesium levels.