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Biomedical subjects

Gordon J Bell

Publications and source records attributed to Gordon J Bell.

At least 19 recordsLinked to original sources
PubMed2006

The effect of varying the time of concentric and eccentric muscle actions during resistance training on skeletal muscle adaptations in women.

This study investigated the effect of manipulating the time to complete both the concentric (CON) and eccentric (ECC) muscle actions during resistance training on strength, skeletal muscle properties and cortisol in women. Twenty-eight women (mean +/- SE age = 24.3 +/- 1.1 year) with strength training experience completed three training sessions per week for 9 weeks. Two sets of four lower body exercises (leg press, parallel squat, knee extension and knee flexion) were completed using 6-8 RM intensity. The long CON (LC) group performed the CON action for 6 s and the ECC action for 2 s, while the long ECC (LE) group completed the CON and ECC phases for 2 and 6 s, respectively. Both groups experienced significant increases in leg press CON only, ECC only and combined ECC and CON maximal strength (1 RM). Immunohistochemical analyses demonstrated that both types I and IIA vastus lateralis fibre areas significantly increased following LC training while only type I fibre area increased following LE training. There was a decrease in MHCIId(x) with a concomitant increase in MHCIIa (P < 0.05) in both groups. Twenty-four hour urinary cortisol significantly increased after LC training only. It was concluded that LC resistance training was more effective than LE for increasing both types I and IIA fibre area and cortisol when time under tension and intensity of muscle actions were matched between the two modes of resistance training in young healthy women.

Adaptation, Physiological↗
PubMed2006

Effects of acute exercise on neutrophils in pediatric acute lymphoblastic leukemia survivors: a pilot study.

PURPOSE: This nonrandomized controlled trial was designed to investigate the effects of acute exercise on neutrophil count and function in children and adolescents receiving maintenance treatment for acute lymphoblastic leukemia (ALL) compared to matched controls. METHODS: Participants (n = 10; 4 ALL patients and 6 healthy matched controls) were males between the ages of 7 to 18 years. On visit 1, participants completed an incremental exercise test to volitional exhaustion on a treadmill to determine peak aerobic fitness (VO(2peak)). On visit 2, participants completed a 30-minute exercise session consisting of an intermittent run-walk on a treadmill at 70% to 85% of VO(2) peak with blood sampling completed at 5 time points: fasting, preexercise, postexercise, 1-hour postexercise, and 2-hour postexercise. RESULTS: A significant increase in absolute neutrophil count from preexercise to postexercise was observed in both groups (P = 0.011). Neutrophil oxidative capacity was significantly depressed in the ALL group at the basal level (P = 0.029), however, it increased in both groups after exercise and stimulation. CONCLUSIONS: This preliminary study suggests that 30 minutes of moderate intensity exercise in ALL patients receiving maintenance therapy provides a similar neutrophil response to that of healthy age and sex-matched controls.

Acute Disease↗
PubMed2006

The effect of a competitive season and environmental factors on pulmonary function and aerobic power in varsity hockey players.

This study examined the effect of a competitive season and environmental factors on pulmonary function and aerobic power in varsity hockey players. Fourteen male subjects completed testing before and after a 7-month varsity hockey season within ice arena conditions. All subjects completed an aerobic power (.)VO(2) (max) test on a cycle ergometer. Pulmonary function tests were performed at rest and 1, 10, 15, and 25 min after the (.)VO(2) (max) test. The arena environment was monitored during testing and throughout the season for temperature, relative humidity, gaseous chemicals, moulds, and fungi. There was no change in (.)VO(2) (max) during the season. The percent change in forced expiratory flow in 1 s (FEV1) post-exercise compared to resting FEV1 and forced vital capacity (FVC) after the (.)VO(2) (max) test were significantly lower after the season. The arena temperature and relative humidity ranged between 13 and 16 degrees C and between 30% and 45% over the course of the season. Sulfur dioxide (0.7-4.5 ppm) was found in the arena and no airborne moulds unique to the dressing room environment were found to exceed Health Canada's guideline of 50 CFU/m(3) for indoor air quality. It was concluded that some hockey players experience limitations to pulmonary function over the course of a competitive season.

Adult↗
PubMed2006

The effect of dietary control and carbohydrate supplementation on the immune and hormonal responses to rowing exercise.

To determine the effect of carbohydrate supplementation on the immune and stress hormone responses to 1 h of strenuous rowing exercise, 22 male subjects were randomly assigned to a placebo (PLA, n = 11) or carbohydrate (CHO, n = 11) group. Subjects completed 3 d of modified dietary intake, a standardized pre-exercise meal, and consumed either a carbohydrate beverage (1 g.kg body mass(-1)) or a non-caloric placebo drink before, during, and after a 1 h rowing trial. Increases were observed in adrenocorticotrophic hormone, cortisol, blood leukocytes, neutrophils, and natural killer cell concentrations and activity, whereas the ability of peripheral blood monouclear cells (PBMCs) to respond (interleukin-2 (IL-2) production) to stimulation was reduced 5 min after exercise in both groups (p < 0.05). Lymphocytes were also elevated, but in the PLA group only (p < 0.05). One hour after exercise, blood leukocytes remained elevated owing to increased neutrophil concentrations, whereas a number of lymphocyte subsets (CD3+, CD3+/4+, CD3+/8+, CD20+, CD25+, CD4+/25+, CD8+/25+) and the ability of PBMCs to respond to stimulation (IL-2, interferon-gamma (IFN-gamma) production) were lower than resting values in both groups (p < 0.05). Carbohydrate supplementation to athletes in the post-prandial state undergoing a 1 h rowing trial resulted in attenuation of the post-exercise increase in peripheral blood lymphocyte concentration, but had little effect on the ability of PBMCs to produce cytokines following stimulation, natural killer cell activity, stress hormone concentrations, exercise performance, or self-reported incidence of illness during the 14 d period following the experimental trial.

Adrenocorticotropic Hormone↗
PubMed2005

Effect of exercise training on C-reactive protein in postmenopausal breast cancer survivors: a randomized controlled trial.

The objective of this study was to determine the effects of exercise training on changes in C-reactive protein (CRP) and other cardiovascular risk factors in postmenopausal breast cancer survivors. Fifty-three postmenopausal breast cancer survivors were randomly assigned to an exercise (n = 25) or control group (n = 28). The exercise group trained on cycle ergometers 3 times per week for 15 weeks. The control group did not train. The primary end point was change in CRP between baseline and week 15. Secondary end points were changes in RHR, HRR, SBP, DBP, TC, LDL-C, HDL-C, TG, and TC:HDL-C ratio. Fifty-two participants completed the trial. Baseline values did not differ between groups except that TG (p = .007) and TC:HDL-C ratio (p = .023) were higher in the exercise group. Intention-to-treat analysis showed that CRP decreased by 1.39 mg/L in the exercise group whereas it increased by 0.10 mg/L in the control group (mean between group change, -1.49 mg/L; 95% CI, -3.09 to 0.10 mg/L; p = .066). Intention-to-treat analysis also showed a clinically and statistically significant difference between groups for change in HRR (mean change, +10.6 beats/min; 95% CI, +3.4 to +17.7 beats/min; p = .004) and clinically but not statistically significant differences between groups for change in RHR (mean change, -5.5 beats/min; 95% CI, -11.5 to +0.5 beats/min; p = .073), SBP (mean change, -5.5 mmHg; 95% CI, -14.5 to +3.4 mmHg; p = .218), DBP (mean change,-3.6 mmHg; 95% CI, -9.3 to +2.1 mmHg; p = .214), and HDL-C (mean change, +0.05 mmol/L; 95% CI, -0.03 to 0.14 mmol/L; p = .214). These data suggest that exercise training may have beneficial effects on CRP and other cardiovascular risk factors in postmenopausal breast cancer survivors. Larger randomized controlled trials are warranted.

Aged↗
PubMed2005

Effect of elk velvet antler supplementation on the hormonal response to acute and chronic exercise in male and female rowers.

To examine the effects of elk velvet antler supplementation (EVA) combined with training on resting and exercise-stimulated hormonal response, male (n = 25) and female (n = 21) rowers ingested either EVA (560 mg/d) or placebo (PL) during 10 wk of training. VO(2max), 2000 m rowing time, leg and bench press strength were determined before and after 5 and 10 wk of training. Serum hormone levels were measured prior to and 5 and 60 min after a simulated 2000 m rowing race. VO(2max)and strength increased and 2000 m times decreased similarly (P < 0.05) with training. There was no significant difference between the EVA and PL group for any hormonal response. Testosterone (males only) and growth hormone (both genders) were higher 5 min after the simulated race (P < 0.05) but returned to baseline at 60 min. Cortisol was higher 5 and 60 min compared to rest (both genders) (P < 0.05) and was higher 60 min post-exercise following 5 and 10 wk of training. It appears that 10 wk of EVA supplementation does not significantly improve rowing performance nor alter hormonal responses at rest or after acute exercise than training alone.

Adult↗
PubMed2005

Randomized controlled trial of exercise and blood immune function in postmenopausal breast cancer survivors.

The objective was to determine the effects of exercise training on changes in blood immune function in postmenopausal breast cancer survivors. Fifty-three postmenopausal breast cancer survivors were randomly assigned to an exercise (n=25) or control group (n=28). The exercise group trained on cycle ergometers three times per week for 15 wk. The control group did not train. The primary end point was change in natural killer cell cytotoxic activity in isolated peripheral blood mononuclear cells. Secondary end points were changes in standard hematological variables, whole blood neutrophil function, the phenotypes of isolated mononuclear cells, estimations of unstimulated and phytohemaglutinin-stimulated mononuclear cell function (rate of [3H]thymidine uptake), and the production of proinflammatory [interleukin (IL)-1alpha, tumor necrosis factor-alpha, IL-6] and anti-inflammatory cytokines (IL-4, IL-10, transforming growth factor-beta1). Statistical tests were two-sided (alpha <0.05). Fifty-two participants completed the trial. Intention-to-treat analyses, which included the baseline value as a covariate, showed significant differences between groups for change in percent specific lysis of a target natural killer cell at all five effector-to-target ratios (adjusted mean between-group change over all 5 effector-to-target ratios = +6.34%; P <0.05 for all comparisons), the lytic activity per cell (adjusted mean between-group change = -2.72 lytic units; P=0.035), and unstimulated [3H]thymidine uptake by peripheral blood lymphocytes (adjusted mean between-group change = +218 per dpm x 10(6) cells; P = 0.007). There were no significant differences between groups for change in any other end point. Exercise training increased natural killer cell cytotoxic activity and unstimulated [3H]thymidine uptake by peripheral blood lymphocytes in postmenopausal breast cancer survivors.

Breast Neoplasms↗
PubMed2004

Effects of strength, endurance and combined training on myosin heavy chain content and fibre-type distribution in humans.

This study investigated the effect of strength training, endurance training, and combined strength plus endurance training on fibre-type transitions, fibre cross-sectional area (CSA) and MHC isoform content of the vastus lateralis muscle. Forty volunteers (24 males and 16 females) were randomly assigned to one of four groups: control (C), endurance training (E), strength training (S), or concurrent strength and endurance training (SE). The S and E groups each trained three times a week for 12 weeks; the SE group performed the same S and E training on alternate days. The development of knee extensor muscle strength was S>SE>E ( P<0.05) and has been reported elsewhere. The reduction in knee extensor strength development in SE as compared to S corresponded to a 6% increase in MHCIIa content ( P<0.05) in SE at the expense of the faster MHCIId(x) isoform ( P<0.05), as determined by electrophoretic analyses; reductions in MHCIId/x content after S or E training were attenuated by comparison. Both S and SE induced three- to fourfold reductions ( P<0.05) in the proportion of type IIA/IID(X) hybrid fibres. S also induced fourfold increases in the proportion of type I/IIA hybrid fibres within both genders, and in a population of fibres expressing a type I/IID(X) hybrid phenotype within the male subjects. Type I/IIA hybrid fibres were not detected after SE. Both S and SE training paradigms induced similar increases (16-19%, P<0.05) in the CSA of type IIA fibres. In contrast, the increase in CSA of type I fibres was 2.9-fold greater ( P<0.05) in S as compared to SE after 12 weeks. We conclude that the interference of knee extensor strength development in SE versus S was related to greater fast-to-slow fibre-type transitions and attenuated hypertrophy of type I fibres. Data are given as mean (SEM) unless otherwise stated.

Adult↗
PubMed2004

Effects of spaceflight on myosin heavy-chain content, fibre morphology and succinate dehydrogenase activity in rat diaphragm.

The present study examined the effect of 14 days of exposure to microgravity during the Spacelab Life Sciences-2 (SLS-2) space shuttle mission on the myosin heavy-chain (MHC) content, fibre size and type distributions and metabolic properties of rat diaphragm. Five adult male Sprague-Dawley rats were exposed to 14 days of microgravity (SF, spaceflight) and compared to five ground-based controls (C). Immunohistochemical analyses using isoform-specific anti-MHC monoclonal antibodies revealed that 14 days of SF did not alter the proportions of type-I, -IIA, -IID/X or -IIB fibres within the crural, sternal or lateral costal regions of the diaphragm; the electrophoretically quantified MHC-isoform contents also remained unchanged. In contrast, the medial gastrocnemius (MG) and tibialis anterior (TA) muscles displayed slow-to-fast fibre type transitions: within the MG the proportion of type-IID/X fibres was reduced by 59% ( P<0.04) and corresponded to a 51% increase ( P<0.03) in type-IIB fibres. Within the TA, the sum of type-IID/X+IIB fibres was elevated by 24% ( P<0.02) at the expense of the slower type-IIA fibres, which decreased by 33% ( P<0.04). Electrophoretic analyses yielded qualitatively similar patterns of transformation. SF did not induce atrophic changes within the diaphragm, MG or TA. Succinate dehydrogenase activity remained unchanged in the crural diaphragm ( P>0.96) but was 34% lower ( P<0.0001) in the TA. We conclude that 14 days of SF did not alter structural or metabolic factors that are known to underlie functional properties of the diaphragm. The findings of the present study show that 14 days of SF does not induce deleterious adaptive changes in the rat diaphragm that occur in hindlimb muscles.

Animals↗
PubMed2004

Acute creatine monohydrate supplementation: a descriptive physiological profile of responders vs. nonresponders.

The purpose of this study was to describe the physiological profile of responders (>20 mmol.kg(-1) dry weight [dw] increase in total intramuscular creatine monohydrate [Cr] + phosphorylated creatine [PCr]) versus nonresponders (<10 mmol.kg(-1) dw increase) to a 5-day Cr load (0.3 g.kg(-1).d(-1)) in 11 healthy men (mean age = 22.7 years). Pre-post 5-day cellular measures included total resting Cr content (Cr + PCr), fiber type composition, and fiber type cross-sectional area (CSA) determined from muscle biopsies of the vastus lateralis. Body mass, daily dietary intake, 24-hour urine outputs, urinary Cr and creatinine (CrN), and strength performance measures (1 repetition maximum [1RM] bench and leg press) were also assessed before and after the 5-day loading period. Results indicated that there were 3 levels of response to the 5-day supplementation: responders (R), quasi responders (QR), and nonresponders (NR) with mean changes in resting Cr + PCr of 29.5 mmol.kg(-1) dw (n = 3), 14.9 mmol.kg(-1) dw (n = 5), and 5.1 mmol.kg(-1) dw (n = 3), respectively. The results support a person-by-treatment interaction to acute Cr supplementation with R possessing a biological profile of lowest initial levels of Cr + PCr, greatest percentage of type II fibers, and greatest preload muscle fiber CSA and fat-free mass. Responders also showed improvement in 1RM leg press scores following the 5-day loading period. NR had higher preload levels of Cr + PCr, less type II muscle fibers, small preload muscle CSA, and lower fat-free mass and displayed no improvements in 1RM strength scores. The results suggest that to be considered a responder to acute oral supplementation, a favorable preexisting biological profile may determine the final extent to which an individual responds to supplementation. Physiologic profiles of nonresponders appear to be different and may limit their ability to uptake Cr. This may help partially explain the reported equivocal performance findings in the Cr supplementation literature.

Adaptation, Physiological↗
PubMed2003

Randomized controlled trial of exercise training in postmenopausal breast cancer survivors: cardiopulmonary and quality of life outcomes.

PURPOSE: To determine the effects of exercise training on cardiopulmonary function and quality of life (QOL) in postmenopausal breast cancer survivors who had completed surgery, radiotherapy, and/or chemotherapy with or without current hormone therapy use. METHODS: Fifty-three postmenopausal breast cancer survivors were randomly assigned to an exercise (n = 25) or control (n = 28) group. The exercise group trained on cycle ergometers three times per week for 15 weeks at a power output that elicited the ventilatory equivalent for carbon dioxide. The control group did not train. The primary outcomes were changes in peak oxygen consumption and overall QOL from baseline to postintervention. Peak oxygen consumption was assessed by a graded exercise test using gas exchange analysis. Overall QOL was assessed by the Functional Assessment of Cancer Therapy-Breast scale. RESULTS: Fifty-two participants completed the trial. The exercise group completed 98.4% of the exercise sessions. Baseline values for peak oxygen consumption (P =.254) and overall QOL (P =.286) did not differ between groups. Peak oxygen consumption increased by 0.24 L/min in the exercise group, whereas it decreased by 0.05 L/min in the control group (mean difference, 0.29 L/min; 95% confidence interval [CI], 0.18 to 0.40; P <.001). Overall QOL increased by 9.1 points in the exercise group compared with 0.3 points in the control group (mean difference, 8.8 points; 95% CI, 3.6 to 14.0; P =.001). Pearson correlations indicated that change in peak oxygen consumption correlated with change in overall QOL (r = 0.45; P <.01). CONCLUSION: Exercise training had beneficial effects on cardiopulmonary function and QOL in postmenopausal breast cancer survivors.

Breast Neoplasms↗
PubMed2003

Development of race profiles for the performance of a simulated 2000-m rowing race.

The purpose of this study was to determine the race profile for a 2000-m simulated rowing race as well as the effect of training and gender on the race profile. Nineteen men and 19 women undertook a 2000-m simulated rowing race before and after 10 weeks of a typical off-season training program for rowing. Velocity was calculated every 200 m and the deviation in velocities from the mean race velocity (MRV) was plotted every 200 m to produce race profiles for each gender before and after training. The three fastest male rowers varied approximately 0.02 m.s from the MRV after training and displayed a constant-pace model. The fastest female rowers displayed an all-out strategy after training, producing large deviations from MRV. Average squared deviations from the mean (SDM) determined that all groups except the fastest females had a reduction in MRV deviation after training. These results suggest that the optimal race profile for a simulated 2000-m rowing race may be different between genders. Training reduces SDM and influences both male and female pacing patterns such that both exhibit a pacing strategy that is more similar to that of elite athletes in other events of similar and shorter duration.

Adult↗
PubMed2003

Effects of exercise training on fasting insulin, insulin resistance, insulin-like growth factors, and insulin-like growth factor binding proteins in postmenopausal breast cancer survivors: a randomized controlled trial.

Insulin, insulin-like growth factors (IGFs) I and II, and IGF binding proteins (IGFBPs) 1 and 3 have been implicated in breast cancer outcomes. We conducted a randomized controlled trial to determine the physiological effects of exercise training on changes in these biological markers in postmenopausal breast cancer survivors. Fifty-three postmenopausal breast cancer survivors were randomly assigned to an exercise (n = 25) or control group (n = 28). The exercise group trained on cycle ergometers three times per week for 15 weeks. The control group did not train. End points included changes in fasting insulin, glucose, insulin resistance, IGF-I, IGF-II, IGFBP-1, IGFBP-3, and IGF-I:IGFBP-3 molar ratio between baseline and week 15. All of the statistical tests were two-sided (alpha = 0.05). Fifty-two participants completed the trial. The exercise group completed 44.3 of 45 (98.4%) prescribed exercise sessions. Baseline hormone concentrations did not differ between groups except that IGF-II was higher in the exercise group (P = 0.011). No significant differences between groups were observed for changes in fasting insulin (+6.3 pmol/liter; P = 0.941), glucose (+0.09 mmol/liter; P = 0.824), insulin resistance (+0.4; P = 0.247), IGF-II (-40.7 ng/ml; P = 0.101), or IGFBP-1 (+1.4 ng/ml; P = 0.774). However, significant differences between groups were observed for changes in IGF-I (-7.4 ng/ml; P = 0.045), IGFBP-3 (+180.5 ng/ml; P = 0.021), and IGF-I:IGFBP-3 molar ratio (-0.006; P = 0.017). Exercise training had significant physiological effects on IGF-I, IGFBP-3, and IGF-I:IGFBP-3 molar ratio in postmenopausal breast cancer survivors. The clinical implications of these findings remain to be defined.

Aged↗
PubMed2002

Electrical stimulation for therapy and mobility after spinal cord injury.

This article reviews the use of therapeutic and functional electrical stimulation in subjects after a spinal cord injury (SCI). Muscles become much weaker and more fatigable, while bone density decreases dramatically after SCI. Therapeutic stimulation of paralyzed muscles for about 1 h/day can reverse the atrophic changes and markedly increase muscle strength and endurance as well as bone density. Functional electrical stimulation can also improve the speed and efficiency of walking in people with an incomplete SCI. Finally, a modified wheelchair is described in which electrical stimulation or residual voluntary activation of leg muscles can produce movements of a footrest that is coupled to the wheels. The wheelchair can provide greater mobility and fitness to persons who are not functional walkers and currently use their arms to propel a wheelchair.

Electric Stimulation Therapy↗
PubMed2002

An experimental investigation of the relation between catastrophizing and activity intolerance.

The present study examined the value of a measure of catastrophizing as a predictor of activity intolerance in response to delayed onset muscle soreness (DOMS). A sample of 50 (17 men, 33 women) sedentary undergraduates participated in an exercise protocol designed to induce muscle soreness and were asked to return 2 days later to perform the same physical maneuvers. Participants performed five strength exercises that emphasized the eccentric component of the muscle contraction in order to induce DOMS. Dependent variables of interest were the proportion reduction in total weight lifted, and the number of repetitions. Analyses revealed that catastrophizing, assessed prior to the first exercise bout, was significantly correlated with negative mood, pain and with reduction in weight lifted. Regression analyses revealed that catastrophizing predicted reductions in weight lifted even after controlling for pain and negative mood. These findings extend previous research in demonstrating that catastrophizing is associated with objective indices of activity intolerance associated with pain. Implications of these findings for understanding pain-related disability are addressed.

Adolescent↗
PubMed2002

Effects of hyperbaric oxygen on recovery from exercise-induced muscle damage in humans.

OBJECTIVE: To determine whether hyperbaric oxygen (HBO) therapy could accelerate recovery from exercise-induced muscle damage in humans. DESIGN: Pretest-posttest design with random assignment to either a treatment (HBO) or placebo control (sham) group. SETTING: University of Alberta and Misericordia Hospital, Edmonton. PARTICIPANTS: 12 healthy male students (24.2 +/- 3.2 years) who were unaccustomed to strenuous eccentric exercise of the calf muscles. INTERVENTIONS: All subjects performed a strenuous eccentric exercise protocol designed to elicit muscle damage within the right gastrocnemius muscle. Subjects subsequently received either HBO (100% oxygen at 253 kPa [2.5 ATA] for 60 min; n = 6) or sham (atmospheric air at 132 kPa [1.3 ATA] for 60 min; n = 6) treatment conditions. The first treatment was administered 3-4 hours after damage, with a second and third at 24 and 48 hours after the first, respectively. MAIN OUTCOME MEASURES: Dependent variables included peak torque at 0.52 radians/s, peak isometric torque, and muscular endurance using isokinetic dynamometry; muscle cross-sectional area using magnetic resonance imaging; inorganic phosphate levels and T2 relaxation time using 31P and 1H magnetic resonance spectroscopy; pain sensation and unpleasantness using the Descriptor Differential Scale. These variables were assessed at baseline and until day 5 postdamage. RESULTS: There was little evidence of a difference in recovery rate between the HBO and sham groups. Faster recovery was observed in the HBO group only for isometric peak torque and pain sensation and unpleasantness. CONCLUSIONS: HBO cannot be recommended as an effective method of treatment of this form of muscle injury.

Adult↗