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Biomedical subjects

A C Fry

Publications and source records attributed to A C Fry.

At least 19 recordsLinked to original sources
PubMed2001

Creatine supplementation and health variables: a retrospective study.

PURPOSE: Long-term safety of creatine supplementation has been questioned. This retrospective study was performed to examine markers related to health, the incidence of reported side effects and the perceived training benefits in athletes supplementing with creatine monohydrate. METHODS: Twenty-six athletes (18 M and 8 F, 24.7 +/- 9.2 y; 82.4 +/- 20.0 kg; 176.5 +/- 8.8 cm) from various sports were used as subjects. Blood was collected between 7:00 and 8:30 a.m. after a 12-h fast. Standard clinical examination was performed for CBC and 27 blood chemistries. Testosterone, cortisol, and growth hormone were analyzed using an ELISA. Subjects answered a questionnaire on dietary habits, creatine supplementation, medical history, training history, and perceived effects of supplementation. Body mass was measured using a medical scale, body composition was estimated using skinfolds, and resting heart rate and blood pressure were recorded. Subjects were grouped by supplementation length or no use: Gp1 (control) = no use (N = 7; 3 F, 4 M); Gp2 = 0.8-1.0 yr (N = 9; 2 F, 7 M); and Gp3 = 1(+) (N = 10; 3 F, 7 M). RESULTS: Creatine supplementation ranged from 0.8--4 yr. Mean loading dose for Gp2 and Gp3 was 13.7 +/- 10.0 and the maintenance dose was 9.7 +/- 5.7 g.d(-)1. Group differences were analyzed using one-way ANOVA. CONCLUSIONS: Expected gender differences were observed. Of the comparisons made among supplementation groups, only two differences for creatinine and total protein (P < 0.05) were noted. All group means fell within normal clinical ranges. There were no differences in the reported incidence of muscle injury, cramps, or other side effects. These data suggest that long-term creatine supplementation does not result in adverse health effects.

Adolescent↗
PubMed2001

Physiological and performance responses to tournament wrestling.

PURPOSE: The purpose of this study was to investigate the physiological and performance responses to a simulated freestyle wrestling tournament after typical weight loss techniques used by amateur wrestlers. METHODS: Twelve Division I collegiate wrestlers (mean +/- SD;19.33 +/- 1.16 yr) lost 6% of total body weight during the week before a simulated, 2-d freestyle wrestling tournament. A battery of tests was performed at baseline and before and immediately after each individual match of the tournament. The test battery included assessment for body composition, reaction/movement time, lower and upper body power and isokinetic strength, and a venous blood sample. RESULTS: Lower body power and upper body isometric strength were significantly reduced as the tournament progressed (P < or = 0.05). Significant elevations in testosterone, cortisol, and lactate were observed after each match (P < or = 0.05). However, there was a significant reduction (P < or = 0.05) in resting testosterone values in the later matches. Norepinephrine increased significantly (P < or = 0.05) after each match, whereas epinephrine increased significantly (P < or = 0.05) after each match except the last match of each day. Plasma osmolality was consistently higher than normal values at all times including baseline, with significant increases observed after each match (P < or = 0.05). CONCLUSIONS: Tournament wrestling augments the physiological and performance decrements of weight loss and its impact is progressive over 2 d of competition. The combined effects of these stresses may ultimately be reflected in a wrestler's ability to maintain physical performance throughout a tournament.

Adolescent↗
PubMed2001

The effects of high-intensity exercise on a 10-second sprint cycle test.

Nine men (25.11 +/- 1.16 years) performed 3 different test sessions. In the control session, subjects performed a 10-second sprint cycle test and 1 repetition maximum (1RM) in the back squat. The 5-minute test session consisted of 10 x 1 repetition in the parallel back squat exercise at 90% of their 1RM, 5 minutes of rest, and then a 10-second sprint cycle test. The 20-minute test session consisted of the same test protocol as the 5-minute test session except that the subjects rested for 20-minutes prior to the sprint cycle test. Significant differences were found in average power and average power relative to body weight (F = 5.684, p = 0.014, and F = 1.258, p = 0.006, respectively) for the 5-minute test session. The authors conclude that this particular squat protocol could have a potential carry-over effect into improvements in 100-m sprint times when performing the squats 5-minutes prior to performance.

Adult↗
PubMed2001

Tachycardia during resistance exercise: a case study.

A male weight-trained (WT) subject (A; age = 21 years, height = 193.6 cm, body weight = 113.4 kg, parallel barbell squat 10 repetition maximum [RM] = 183.7 kg) and a group of 18 similarly trained men (WT; X +/- SD; age = 24.7 +/- 3.0 years, height = 180.2 +/- 4.3 cm, body weight = 86.9 +/- 10.7 kg, 10 RM = 127.9 +/- 28.6 kg) were monitored during a barbell squat resistance exercise session (50% - 100% 10 RM) and a graded exercise test on a cycle ergometer. Compared with the WT group, heart rate (HR) for subject A was consistently > or =2 SD greater during resistance exercise (peak HR for 100% 10 RM = 212 b.min(-1) and 165.3 +/- 16.2 b.min(-1)). The graded exercise test resulted in similar HR responses for both A and controls. Subject A's augmented HR was present only during the pressure load of heavy resistance exercise, and not during the volume load of endurance exercise. The data suggest that subject A may be utilizing a different mechanism for heart rate regulation during resistance exercise.

Adult↗
PubMed2000

The effects of 10 days of spaceflight on the shuttle Endeavor on predominantly fast-twitch muscles in the rat.

The primary purpose of this investigation was to determine the effects of microgravity on muscle fibers of the predominantly fast-twitch muscles in the rat. Cross sectional area and myosin heavy chain (MHC) composition were assessed in order to establish the acute effects of microgravity associated with spaceflight. The extensor digitorum longus (EDL) and gastrocnemius muscles were removed from 12 male Fisher 344 rats which had undergone 10 days of spaceflight aboard the space shuttle Endeavor and from 12 age- and weight-matched control animals. Both groups of animals received similar amounts of food and water and were synchronized for photoperiods, environmental temperature, and humidity. Significant (P < 0.05) reductions in muscle fiber size were observed in the gastrocnemius (fiber types I, IIA, IIDB, and IIB) and EDL (fiber type IIB) muscles after spaceflight. Significant MHC isoform transformations also resulted during this brief period of microgravity exposure with a significant decrease in MHC IId isoform in the EDL muscle. A significant decrease was also observed in the MHC IId isoform in the superficial (white) component of the gastrocnemius muscle after spaceflight, although no alterations in MHC profile were demonstrated in the deep (red) component of this muscle. These findings highlight the rapid plasticity of skeletal muscle during short-term spaceflight. If such pronounced adaptations to spaceflight also occur in humans, then astronauts are likely to suffer severe decrements in skeletal muscle performance with long-term space flight and upon return to earth after both short- and long-term missions. Thus, countermeasures aimed at slowing or even preventing muscle fiber atrophy are warranted.

Animals↗
PubMed1999

Fiber type composition of four hindlimb muscles of adult Fisher 344 rats.

The limb and trunk muscles of adult rats express four myosin heavy chain (MHC) isoforms, one slow (MHCI) and three fast (MHCIIa, MHCIId, and MHCIIb). The distribution of these isoforms correlates with fiber types delineated using myofibrillar actomyosin adenosine triphosphatase (mATPase) histochemistry. For example, type I fibers express MHCI and fiber types IIA, IID, and IIB express MHCIIa, MHCIId, and MHC-IIb, respectively. Fibers containing only one MHC isoform have been termed "pure" fibers. Recent evidence suggests that a population of "hybrid" fibers exist in rat skeletal muscle which contain two MHC isoforms. The purpose of the present investigation was to document the entire range of histochemically defined "pure" and "hybrid" fiber types in untreated muscles of the young adult Fisher 344 rat hindlimb. The selected hindlimb muscles (soleus, tibialis anterior, extensor digitorum longus, and gastrocnemius muscles) were removed from 12 male rats and analyzed for muscle fiber type distribution, cross-sectional area, and MHC content. Care was taken to delineate eight fiber types (I, IC, IIC, IIA, IIAD, IID, IIDB, and IIB) using refined histochemical techniques. Hybrid fibers were found to make up a considerable portion of the muscles examined (a range of 8.8-17.8% of the total). The deep red portion of the gastrocnemius muscle contained the largest number of hybrid fibers, most of which were the fast types IIAD (8.5+/-2.8%) and IIDB (5.2+/-2.3%). In conclusion, hybrid fibers make up a considerable portion of normal rat limb musculature and are an important population that should not be ignored.

Animals↗
PubMed1999

Acute hormonal responses to a single bout of heavy resistance exercise in trained power lifters and untrained men.

The purpose of this study was to investigate the acute responses of both stress and fluid regulatory hormones to a single bout of resistance exercise in both trained and untrained men. Seven competitive power lifters (PL) and 12 untrained subjects (UT) performed one set of the leg press exercise to exhaustion at 80% of their respective one-repetition maximum. Blood samples were obtained twice prior to exercise (at P1 and P2), immediately postexercise (IP), and at 5 minutes postexercise (5PE). Compared to P1 and P2, plasma epinephrine, norepinephrine, dopamine, atrial peptide, osmolality, and blood lactic acid increased significantly (p < or = 0.05) at IP. Plasma epinephrine, norepinephrine, atrial peptide, and blood lactic acid concentrations remained elevated at 5PE compared to P1 and P2. Plasma renin activity and angiotensin II were significantly elevated at 5PE compared to P1, P2, and IP, and this increase was significantly greater in PL compared to UT at 5PE. These data indicate that an acute bout of resistance exercise dramatically affects secretion of stress and fluid regulatory hormones.

Adrenergic alpha-Agonists↗
PubMed1998

The effects of short-term resistance training on endocrine function in men and women.

This investigation examined hormonal adaptations to acute resistance exercise and determined whether training adaptations are observed within an 8-week period in untrained men and women. The protocol consisted of a 1-week pre-conditioning orientation phase followed by 8 weeks of heavy resistance training. Three lower-limb exercises for the quadriceps femoris muscle group (squat, leg press, knee extension) were performed twice a week (Monday and Friday) with every other Wednesday used for maximal dynamic 1 RM strength testing. Blood samples were obtained pre-exercise (Pre-Ex), immediately post-exercise (IP), and 5 min post-exercise (5-P) during the first week of training (T-1), after 6 weeks (T-2) and 8 weeks (T-3) of training to determine blood concentrations of whole-blood lactate (LAC), serum total testosterone (TT), sex-hormone binding globulin (SHBG), cortisol (CORT) and growth hormone (GH). Serum TT concentrations were significantly (P < or = 0.05) higher for men at all time points measured. Men did not demonstrate an increase due to exercise until T-2. An increase in pre-exercise concentrations of TT were observed both for men and women at T-2 and T-3. No differences were observed for CORT between men and women; increases in CORT above pre-exercise values were observed for men at all training phases and at T-2 and T-3 for women. A reduction in CORT concentrations at rest was observed both in men and women at T-3. Women demonstrated higher pre-exercise GH values than men at all training phases; no changes with training were observed for GH concentrations. Exercise-induced increases in GH above pre-exercise values were observed at all phases of training. Women demonstrated higher serum concentrations of SHBG at all time points. No exercise-induced increases were observed in men over the training period but women increased SHBG with exercise at T-3. SHBG concentrations in women were also significantly higher at T-2 and T-3 when compared to T-1 values. Increases in LAC concentrations due to exercise were observed both for men and women for all training phases but no significant differences were observed with training. These data illustrate that untrained individuals may exhibit early-phase endocrine adaptations during a resistance training program. These hormonal adaptations may influence and help to mediate other adaptations in the nervous system and muscle fibers, which have been shown to be very responsive in the early phase of strength adaptations with resistance training.

Adult↗
PubMed1998

Pituitary-adrenal-gonadal responses to high-intensity resistance exercise overtraining.

Weight-trained men [OT; n = 11; age = 22.0 +/- 0.9 (SE) yr] resistance trained daily at 100% one-repetition maximum (1-RM) intensity for 2 wk, resulting in 1-RM strength decrements and in an overtrained state. A control group (Con; n = 6; age = 23.7 +/- 2.4 yr) trained 1 day/wk at a low relative intensity (50% 1 RM). After 2 wk, the OT group exhibited slightly increased exercise-induced testosterone (preexercise = 26.5 +/- 1.3 nmol/l, postexercise = 29.1 +/- 5.9 nmol/l) and testosterone-to-cortisol ratio (preexercise = 0. 049 +/- 0.007 nmol/l, postexercise = 0.061 +/- 0.006 nmol/l) and decreased exercise-induced cortisol (preexercise = 656.1 +/- 98.1 nmol/l, postexercise = 503.1 +/- 39.7 nmol/l). Serum concentrations for growth hormone and plasma peptide F [preproenkephalin (107-140)] were similar for both groups throughout the overtraining period. This hormonal profile is distinctly different from what has been previously reported for other types of overtraining, indicating that high-relative-intensity resistance exercise overtraining may not be successfully monitered via circulating testosterone and cortisol. Unlike overtraining conditions with endurance athletes, altered resting concentrations of pituitary, adrenal, or gonadal hormones were not evident, and exercise-induced concentrations were only modestly affected.

Adult↗
PubMed1997

Differential titin isoform expression in human skeletal muscle.

Mammalian skeletal muscle expresses at least two isoforms of the cytoskeletal protein titin (connectin; MW approximately 3000 kDa). These isoforms are associated with different passive force curves, and thus may affect physical performance. To study the distribution of titin and its possible influence on performance in humans, muscle biopsies were obtained from 15 males (mean +/- SE; age = 25.4 +/- 2.9 years, height = 177.7 +/- 1.8 cm, weight = 76.5 +/- 2.2 kg). Two biopsies were obtained on separate occasions from both the right and left vastus lateralis, and one biopsy each from the lateral head of the right gastrocnemius and the right soleus, with all biopsies handled identically. Fibre type analyses were performed via mATPase histochemistry. Expression of titin and myosin heavy chain isoforms were determined by SDS-PAGE. Titin bands in the resulting gels were highly repeatable and were verified by migration patterns, as well as Western blot analysis. Two groups of subjects were identified: group 1 (n = 10) expressed only one titin isoform (titin-1) in all biopsies, and group 2 (n = 5) expressed two titin isoforms (titin-1 and titin-2) in all biopsies. No significant differences (P > 0.05) between groups were observed for percentage fibre types, percentage fibre type areas, fibre type cross-sectional areas, and percentage myosin heavy chain expression when comparing individual muscles, sampling times or bilateral comparisons. This is the first report of differential titin isoform expression in healthy, mature human skeletal muscle, but it is not clear why this occurs or what influence this may have on performance.

Adult↗
PubMed1997

The effects of gamma-oryzanol supplementation during resistance exercise training.

To determine the effectiveness of gamma-oryzanol supplementation, weight-trained males were randomly divided into supplemented (G-O) and control placebo (Con) groups. The G-O group ingested 500 mg.day-1 of gamma-oryzanol according to manufacturer's instructions. Test batteries were administered before (T1), after 4 weeks (T2), and after 9 weeks (T3) of a periodized resistance exercise program. Both groups demonstrated significant increases in 1 repetition maximum muscular strength (bench press and squat) and vertical jump power, with no differences between the groups. No differences between groups were observed for measures of circulating concentrations of hormones (testosterone, cortisol, estradiol, growth hormone, insulin, beta-endorphin), minerals (calcium, magnesium), binding protein (albumin), or blood lipids (total cholesterol, triglycerides, HDL-cholesterol). Resting cardiovascular variables decreased similarly for both groups. These data suggest that 9 weeks of 500 mg.day-1 of gamma-oryzanol supplementation does not influence performance or related physiological parameters in moderately weight-trained males.

Adult↗
PubMed1997

Resistance exercise overtraining and overreaching. Neuroendocrine responses.

Overtraining is defined as an increase in training volume and/or intensity of exercise resulting in performance decrements. Recovery from this condition often requires many weeks or months. A shorter or less severe variation of overtraining is referred to as overreaching, which is easily recovered from in just a few days. Many structured training programmes utilise phases of overreaching to provide variety of the training stimulus. Much of the scientific literature on overtraining is based on aerobic activities, despite the fact that resistance exercise is a large component of many exercise programmes. Chronic resistance exercise can result in differential responses to overtraining depending on whether either training volume or training intensity is excessive. The neuroendocrine system is a complex physiological entity that can influence many other systems. Neuroendocrine responses to high volume resistance exercise overtraining appear to be somewhat similar to overtraining for aerobic activities. On the other hand, excessive resistance training intensity produces a distinctly different neuroendocrine profile. As a result, some of the neuroendocrine characteristics often suggested as markers of overtraining may not be applicable to some overtraining scenarios. Further research will permit elucidation of the interactions between the neuroendocrine system and other physiological systems in the aetiology of performance decrements from overtraining.

Adrenocorticotropic Hormone↗
PubMed1994

Correlation between percentage fiber type area and myosin heavy chain content in human skeletal muscle.

Histochemical methods are routinely used to delineate skeletal muscle fiber types. In the present investigation, this qualitative determination of fiber type composition was compared to the electrophoretically determined myosin heavy chain (MHC) content from a large number of human muscle biopsy samples. Biopsies were taken from the vastus lateralis muscle at the beginning and every 2 weeks during 8 weeks of high-intensity resistance training from men (n = 13) and woman (n = 8). Muscle was also extracted from nontraining men (n = 7) and women (n = 5) at the same periods. Six muscle fiber types (I, IC, IIAC, IIA, IIAB, and IIB) were determined using basic myofibrillar adenosine triphosphatase histochemistry. Cross-sectional areas were determined for the three major fiber types (I, IIA, and IIB) and used to calculate the percentage area of these types. Electrophoretic techniques were used to separate and quantify the percentage MHC content in these same biopsy samples, and these data were then used to compare with the percentage fiber type area. Correlation analyses suggest a relationship between the histochemically assessed percentage fiber type area and the electrophoretically assessed MHC content in human limb musculature. However, because of possible histochemical misclassification of some fibers (especially in trained muscle) both techniques may be essential in yielding important information about fiber type composition and possible fiber type transformations.

Adult↗
PubMed1994

Endocrine responses to overreaching before and after 1 year of weightlifting.

Nine elite male junior weightlifters (mean age 17.6 +/- 0.3 yrs) performed weightlifting tests before (Test 1) and after (Test 2) 1 week of increased training volume (overreaching) and repeated the protocol after 1 year of their training program. Strength increased by Year 2 (p < 0.05) but did not change during either week of increased training volume. The 1-week overreaching stimulus resulted in attenuated exercise-induced testosterone concentrations during Year 1, but augmented exercise-induced testosterone concentrations during Year 2. Testosterone concentrations at 7 a.m. decreased for only Year 1. For both years, the 1-week overreaching stimulus increased cortisol at 7 a.m, indicative of the increased training volumes. Testosterone/cortisol was not affected by increased training volume for either year. One year of chronic weightlifting and prior exposure to the overreaching stimulus appears to decrease the detrimental effects of stressful training on the endocrine system.

Adaptation, Physiological↗
PubMed1994

Skeletal muscle adaptations during early phase of heavy-resistance training in men and women.

An 8-wk progressive resistance training program for the lower extremity was performed twice a week to investigate the time course for skeletal muscle adaptations in men and women. Maximal dynamic strength was tested biweekly. Muscle biopsies were extracted at the beginning and every 2 wk of the study from resistance-trained and from nontrained (control) subjects. The muscle samples were analyzed for fiber type composition, cross-sectional area, and myosin heavy chain content. In addition, fasting blood samples were measured for resting serum levels of testosterone, cortisol, and growth hormone. With the exception of the leg press for women (after 2 wk of training) and leg extension for men (after 6 wk of training), absolute and relative maximal dynamic strength was significantly increased after 4 wk of training for all three exercises (squat, leg press, and leg extension) in both sexes. Resistance training also caused a significant decrease in the percentage of type IIb fibers after 2 wk in women and 4 wk in men, an increase in the resting levels of serum testosterone after 4 wk in men, and a decrease in cortisol after 6 wk in men. No significant changes occurred over time for any of the other measured parameters for either sex. These data suggest that skeletal muscle adaptations that may contribute to strength gains of the lower extremity are similar for men and women during the early phase of resistance training and, with the exception of changes in the fast fiber type composition, that they occur gradually.

Adaptation, Physiological↗
PubMed1994

Catecholamine responses to short-term high-intensity resistance exercise overtraining.

Seventeen weight-trained males were divided into an overtraining group [OT; n = 11; age = 22.0 +/- 0.9 (SE) yr] that weight trained their legs daily for 2 wk with 100% 1 repetition maximum relative intensity on a squat machine and a control group (n = 6; age = 23.7 +/- 2.4 yr) that exercised 1 day/wk with low relative intensity (50% 1 repetition maximum). Test batteries including strength assessments and resting and exercise-induced concentrations of epinephrine and norepinephrine were conducted at the beginning, middle, and end (tests 1-3, respectively) of the study. Strength capabilities decreased by test 3 for the OT group (P < 0.05). Resting catecholamine concentrations did not change for either group during the study, whereas exercise-induced concentrations of both epinephrine (test 1 = 3,407.9 +/- 666.6 pmol/l, test 2 = 7,563.7 +/- 1,210.6 pmol/l, test 3 = 6,931.6 +/- 919.3 pmol/l) and norepinephrine (test 1 = 42.9 +/- 7.4 nmol/l, test 2 = 70.0 +/- 8.8 nmol/l, test 3 = 85.2 +/- 14.5 nmol/l) significantly increased by tests 2 and 3 for only the OT group. Correlation coefficients suggested decreased responsitivity of skeletal muscle to sympathetic nervous system activity. It appears that altered exercise-induced sympathetic nervous system activity accompanies high relative intensity resistance exercise overtraining and may be among the initial responses to the onset of the previously theoretical sympathetic overtraining syndrome.

Adult↗
PubMed1994

Effects of sprint cycle training on human skeletal muscle.

Eleven men sprint trained two to three times per week for 6 wk to investigate possible exercise-induced slow-to-fast fiber type conversions. Six individuals served as controls. Both groups were tested at the beginning and end of the study to determine anaerobic performance and maximal oxygen consumption. In addition, pre- and postbiopsies were extracted from the vastus lateralis muscle and were analyzed for fiber type composition, cross-sectional area, and myosin heavy chain (MHC) content. No significant changes were found in anaerobic or aerobic performance variables for either group. Although a trend was found for a decrease in the percentage of type IIb fibers, high-intensity sprint cycle training caused no significant changes in the fiber type distribution or cross-sectional area. However, the training protocol did result in a significant decrease in MHC IIb with a concomitant increase in MHC IIa for the training men. These data appear to support previous investigations that have suggested exercise-induced adaptations within the fast fiber population (IIb-->IIa) after various types of training (endurance and strength).

Adult↗