Single Resistance Exercise Session Research Articles

Insulin sensitivity in response to a single resistance exercise session in apparently healthy individuals.

Regular resistance exercise completed for a number of weeks has been shown to increase insulin sensitivity and reduce the risk of diabetes-related complications. However, the acute responses to resistance exercise have not been adequately investigated in relation to training frequency. To investigate the changes to insulin sensitivity in apparently healthy individuals following a single session of unaccustomed resistance exercise. Ten sedentary, apparently healthy individuals performed a baseline oral glucose tolerance test and maximal strength testing. Participants then performed a single session of moderate-high intensity resistance exercise which was followed by 4 consecutive days of oral glucose tolerance testing, for which participants replicated their initial diet. Mean estimated insulin sensitivity change scores from baseline values and their 95% confidence intervals were compared to the previously determined values for a clinically meaningful change. Two participants were identified as having hyperinsulinemia and their data were therefore removed from the main analysis. There was a clinically meaningful increase in insulin response (mean >7237 pmol·l⁻¹·120 min⁻¹) on all days following the exercise session and a clinically meaningful increase in glucose response (mean >81 mmol·l⁻¹·120 min⁻¹) on only the 3rd day following exercise. These changes suggest a potentially adverse short-term effect. Additionally, the 2 individuals with hyperinsulinemia displayed more extreme results. These results suggest that insulin sensitivity may be impaired following a single session of unaccustomed resistance exercise for approximately 4 days in healthy untrained, older individuals. Further research is required for individuals with hyperinsulinemia.

The impact of one session resistance exercise on plasma adiponectin and RBP4 concentration in trained and untrained healthy young men

We designed this study, to investigate the predicting effect of a single resistance exercise session on serum level of RBP4 and adiponectin in trained and untrained subjects and to evaluate whether regular training may affect the response of these adipokines to exercise. Thirty four healthy young male students including 19 trained and 15 untrained participated in this study; each group was then randomly assigned to intervention and control groups. The exercise session prolonged 120 minutes intensive resistance program at 70%-80% of 1RM. The blood samples were collected just before the start of training program and 4 hours post exercise to evaluate concentration of adiponectin, RBP4 and CRP as well as other metabolic markers. The serum level of adiponectin, RBP4 and CRP was not significantly different between trained and untrained groups at baseline. More over four hours post exercise adipokines concentration and CRP didn't differ between groups. Adjusted regression model showed, basal adiponectin (β=0.59, p=<0.001) and HDL cholesterol (β=0.28, p=0.09) were the main predictors of post exercise adiponectin concentration. In addition, the basic level of RBP4 appeared to be the only predictor of after exercise RBP4 concentration (β=0.46, p=0.02). Neither one session of high intensity resistance exercise nor long term training had predicting effect on post exercise adiponectin and RBP4 concentration in healthy young men. In the other hand, the beneficial effect of acute resistance exercise training may not be reflected by changes in adiponectin, RBP4 and CRP concentration in healthy young individual no matter they trained or untrained.

Resistance Exercise and Lipoproteins in Postmenopausal Women

The specific aims of this study were to quantify the effects of 12 weeks of resistance training, as well as a single session of resistance exercise on lipids and lipoproteins in obese, postmenopausal women. 21 obese, postmenopausal women, not on hormone replacement therapy (age=65.9 ± 0.5 yr; BMI=32.7 ± 0.8 kg/m(2)), were randomly assigned to control (n=12) and exercise (n=9) groups matched for age and BMI. For 12 weeks, 3 days/week, the exercise group performed 10 whole body resistance exercises (3 sets at 8-RM). Fasting (10 h) blood samples were collected immediately prior to and 24 h after the first and last exercise and control session. Serum was assayed for concentrations of total cholesterol, triglycerides, LDL-C, HDL-C, HDL 2-C, HDL 3-C, non-HDL-C and TC:HDL and LDL:HDL ratios. The exercise group exhibited a significant (P<0.01) improvement in muscular strength, but no change in BMI, body mass or body composition post-training. Total cholesterol, LDL-C and non-HDL-C were significantly (P<0.05) lower in the exercise compared to the control group following the 12 weeks of resistance training. Whole body resistance training provides obese, postmenopausal women a non-pharmacological approach for the reduction of lipid and lipoprotein-cholesterol concentrations.

Influência do estado de treinamento sobre o comportamento da pressão arterial após uma sessão de exercícios com pesos em idosas hipertensas

INTRODUÇÃO: São escassas as investigações envolvendo o efeito hipotensivo pós-esforço dos exercícios com pesos em idosos e hipertensos. OBJETIVO: Verificar o comportamento da pressão arterial sistólica (PAS), diastólica (PAD) e média (PAM) após uma sessão de exercícios com pesos em idosas hipertensas treinadas e não treinadas. MÉTODOS: Participaram do estudo 15 mulheres (66 ± 4 anos; 63,9 ± 9,1kg; 1,6 ± 0,1m) divididas em grupo treinadas (GT; n = 6) e grupo não treinadas (GNT; n = 9). A amostra foi submetida aleatoriamente a uma sessão controle (SC), na qual permaneceram sentadas em repouso por 40 min e a uma sessão experimental (SE), realizando sete exercícios com pesos executados em duas séries de 10-15 repetições máximas. A pressão arterial foi verificada pelo método auscultatório após 10 min de repouso no período pré-exercício e em ciclos de 15 min durante 1h após o término da sessão. RESULTADOS: Não foram encontradas diferenças entre os grupos para as variáveis analisadas no período pré-exercício. A análise de variância para medidas repetidas identificou, no GT, PAS significativamente menor no 30º min após o exercício comparado com o repouso (P = 0,03) durante a SE e nenhuma diferença na SC. O GNT apresentou reduções na PAS (P &lt; 0,001) e na PAM (P &lt; 0,01) nos 15, 30, 45 e 60 min pós-esforço e na PAD (P = 0,02) nos 15º e 30º min, comparados com as medidas de repouso, durante a SE. Na SC houve aumentos na PAS (P = 0,006) e na PAM (P = 0,04) imediatamente após e nos 15, 45 e 60 min pós-exercício. CONCLUSÃO: Os resultados indicaram que uma sessão de exercícios com pesos é capaz de promover hipotensão pós-exercício em mulheres idosas e hipertensas, sendo mais consistente nas não treinadas.

Responses Of Lipids And Lipoproteins Following Acute And Training Resistance Exercise In Obese Postmenopausal Women

Int J Exerc Sci 2(1): S4, 2009.A single aerobic session and aerobic training can favorably modify lipids and lipoproteins in postmenopausal women, but the effects of a single resistance exercise session (RE) and resistance training (RT) remain equivocal. PURPOSE: To determine the acute effects of RE and chronic effects of 12 weeks of RT on lipid and lipoprotein-cholesterol concentrations in obese, postmenopausal women. METHODS: Sedentary, obese, non-smoking, postmenopausal women, not taking HRT, were divided into either an exercise group (E, n = 10; age = 65.7 ± 1.8 y; BMI = 32.6 ± 3.5 kg/m2) or control group (C, n = 11; age = 66.1 ± 3.0 y; BMI = 32.9 ± 4.3 kg/m2). Fasting (12 hr) blood samples were collected prior to and 24 hr after the first (BT) and last (AT) exercise session, and at the same time points for C. E performed ten upper and lower body resistance exercises (3 sets, 8 rep/set, 80% 1-RM) 3 times per week for 12 weeks; while C attended education classes twice per week for 12 weeks. Serum was assayed for total cholesterol, triglycerides, LDL-C, HDL-C, HDL2-C, HDL3-C concentrations. A 2 x 2 x 2 (group x training period x time) MANOVA was to determine changes in lipid and lipoprotein variables. A 2 x 2 (group x time) repeated measures ANOVA was used to assess body composition. RESULTS: The MANOVA revealed no significant changes in serum lipids or lipoproteins following RE or RT. No changes in body composition were observed post-training (P > 0.05). Variable Pre-BT 24 hr BT Pre-AT 24 hr AT TC (mg/dl) C E 189 ± 28 217 ± 55 205 ± 40 212 ± 49 201 ± 48 207 ± 105 206 ± 42 195 ± 106 Tg (mg/dl) C E 107 ± 42 114 ± 40 96 ± 49 103 ± 25 116 ± 49 129 ± 92 112 ± 45 102 ± 48 LDL-C (mg/dl) C E 112 ± 26 140 ± 51 129 ± 37 137 ± 41 118 ± 40 127 ± 89 124 ± 41 120 ± 88 HDL-C (mg/dl) C E 55 ± 16 55 ± 12 57 ± 14 55 ±16 60 ± 13 53 ± 15 60 ± 16 54 ± 17 HDL2-C (mg/dl) C E 36 ± 12 36 ± 10 35 ± 10 34 ± 13 35 ± 12 33 ± 14 33 ± 16 35 ± 13 HDL3-C (mg/dl) C E 19 ± 9 19 ± 5 21 ± 7 21 ± 6 25 ± 6 20 ± 5 26 ± 6 20 ± 7 CONCLUSION: These data suggest that a single RE session and a 12-week RT program have no effect on lipids and lipoproteins. Compared to the effects of aerobic training, resistance exercise related changes in body composition may be necessary to modify lipids and lipoproteins in obese postmenopausal women. TEXAS AMERICAN COLLEGE OF SPORTS MEDICINE 2009 CONFERENCE

POST‐RESISTANCE EXERCISE HYPOTENSION IN SPONTANEOUSLY HYPERTENSIVE RATS IS MEDIATED BY NITRIC OXIDE

1. Postexercise hypotension (PEH) plays an important role in the non-pharmacological treatment of hypertension. It is characterized by a decrease in blood pressure (BP) after a single bout of exercise in relation to pre-exercise levels. 2. The present study investigated the effect of a single session of resistance exercise, as well as the effect of nitric oxide (NO) and the autonomic nervous system (ANS), in PEH in spontaneously hypertensive rats (SHR). 3. Catheters were inserted into the left carotid artery and left jugular vein of male SHR (n = 37) for the purpose of measuring BP or heart rate (HR) and drug or vehicle administration, respectively. Haemodynamic measurements were made before and after acute resistance exercise. The roles of NO and the ANS were investigated by using N(G)-nitro-L-arginine methyl ester (L-NAME; 15 mg/kg, i.v.) and hexamethonium (20 mg/kg, i.v.) after a session of acute resistance exercise. 4. Acute resistance exercise promoted a pronounced reduction in systolic and diastolic BP (-37 +/- 1 and -8 +/- 1 mmHg, respectively; P < 0.05), which was suppressed after treatment with L-NAME. The reduction in systolic BP caused by exercise (-37 +/- 1 mmHg) was not altered by the administration of hexamethonium (-38 +/- 2 mmHg; P > 0.05). After exercise, the decrease in diastolic BP was greater with hexamethonium (-26 +/- 1 mmHg; P < 0.05) compared with the decrease caused by exercise alone. 5. The results suggest that acute resistance exercise has an important hypotensive effect on SHR and that NO plays a crucial role in this response.

A Single Session of Resistance Exercise Induces Oxidative Damage in Untrained Men

During exercise, the production of reactive oxygen and nitrogen species significantly increases. The aim of the present study was to investigate the effects of a single session of resistance exercise on antioxidant capacity, oxidative damage, and inflammation. Muscle biopsies, urine, and blood samples were collected from seven healthy men before and after a single bout of resistance exercise. A single session of resistance exercise was found to induce oxidative damage, as shown by a 40% increase in the concentration of urinary F2alpha-isoprostanes (P < 0.05). Total antioxidant capacity of plasma increased 16% (P < 0.05). This increase seemed to be predominantly attributable to an increase in plasma uric acid concentrations of 53% (P < 0.05). Similar to uric acid, but to a relatively much smaller extent, vitamin C and vitamin E levels in plasma were also elevated (P < 0.05). Moreover, the erythrocyte glutathione (GSH) [corrected] concentration increased 47% during exercise (P < 0.05). Also in skeletal muscle, uric acid levels were found to increase after exercise (P < 0.05). Moreover, 30 min after exercise, skeletal muscle glutathione S-transferase (GST) and glutathione reductase activity increased 28 and 42%, respectively (P < 0.05). Skeletal muscle reduced GSH [corrected] and GSH [corrected] disulphide (GSSG) concentrations were not affected by exercise. The Nuclear Factor kappa B (NF-kappaB) activity in peripheral blood mononuclear cells (PBMC) was not increased by exercise, indicating that a NF-kappaB-mediated inflammatory response does not occur. We conclude that a single session of resistance exercise induces oxidative damage despite an adaptive increase in antioxidant capacity of blood and skeletal muscle.

Efeitos hemodinâmicos e vasculares do treinamento resistido: implicações na doença cardiovascular

Resistance training has been proposed as a possible strategy for cardiovascular prevention and rehabilitation, and in this context, this review describes the cardiovascular effects mediated by this type of intervention. Increments in both muscular strength and capacity to perform daily tasks are well-characterized benefits of this type of training. More recently, studies using hemodynamic evaluation have shown cardiovascular stability in patients with coronary disease or heart failure during the performance of resistance exercise, with no apparent detriment to ventricular function or exacerbated increase in exercise blood pressure. Additionally, resting blood pressure also seems to be influenced by chronic resistance training, with a slight reduction in both systolic blood pressure (SBP) and diastolic blood pressure (DBP). The measurement of pressure levels after a single resistance exercise session shows the occurrence of post-exercise hypotension in normal and hypertensive individuals; however, there is controversy as to the intensity of the effort necessary to induce this effect. Recently, intervention studies have investigated resistance exercise effects on vascular variables as arterial compliance and endothelial function. Despite the small number of experiments available, evidence has shown a potential influence of resistance training on the reduction of arterial compliance. On the other hand, peripheral blood flow is increased after resistance training, whereas the endothelial function seems to be improved especially after combined aerobic and resistance training. Additional research is necessary for an analysis of the efficacy of this intervention on validated outcomes, and for a greater understanding of the physiological mechanisms responsible for vascular adaptations.

ERK MAP Kinase Pathway Activity After Heavy Resistance Exercise

This study evaluated a single session of heavy resistance exercise on the activity of the ERK MAPK pathway. Seven males performed 3 sets of 8–10 repetitions at 75%–80% 1-RM on the squat, leg press, and leg extension exercises (REX) while four served as a control (CON). Muscle biopsies were obtained 30 min pre-exercise (30MPRE), 30 min post-exercise (30MPST), and at 6 hr post-exercise (6HPST). Total and phosporylated levels of MEK1 and ERK 1/2 were determined with ELISA and total and phosphorylated Raf-1 determined with immunoblotting. Data were analyzed with two-way repeated measures ANOVA (p < 0.05). No significant changes were noted for CON. However, when compared to pre-exercise, REX underwent increases in Raf-1, MEK 1, and ERK 1/2 activation at 30MPST (p < .05) that were also greater than CON. A single session of heavy resistance exercise increases the activity of the ERK MAPK pathway extending from Raf-1 to ERK 1/2.

Increased Postprandial Triacylglycerol Concentrations following Resistance Exercise

There is conflicting evidence whether a single bout of resistance exercise performed the day before a test meal can lower postprandial triacylglycerol (TAG) concentrations. The present study examined the effect of a single session of resistance exercise, performed the same day as a test meal, on postprandial TAG concentrations in resistance-trained males. Ten healthy males aged 25 (SD 2.6) yr performed two trials at least 1 wk apart in a counterbalanced, randomized design. In each trial, participants consumed a test meal (0.89 g of fat, 1.23 g of carbohydrate, 0.4 g of protein, 60 kJ.kg body mass). Before one meal, participants performed a 90-min bout of resistance exercise. Before the other meal, participants were inactive (control trial). Resistance exercise was performed using free weights and included three sets of 12 repetitions of each of 10 exercises. Sets were performed at 80% of 12-repetition maximum with a 3-min work and rest interval. Venous blood samples were obtained in the fasted state and for 5 h postprandially. Total area under the plasma TAG concentration versus time curve was higher (Student's t-test P = 0.008) on the exercise than control trial (mean +/- SE: 11.76 +/- 1.64 vs 7.94 +/- 1.08 mmol x L(-1) x 5 h(-1), respectively). Total area under the plasma myoglobin concentration versus time curve was higher (Student's t-test P = 0.010) on the exercise than control trial (16.68 +/- 3.34 vs 6.80 +/- 0.64 nmol x L(-1) x 5 h(-1); respectively). A single bout of resistance exercise can cause a transient elevation in postprandial TAG concentrations. The elevations in plasma myoglobin suggest postexercise muscle damage. Further investigation is needed to see if these findings are linked.

Increase in S6K1 phosphorylation in human skeletal muscle following resistance exercise occurs mainly in type II muscle fibers

To investigate the in vivo effects of resistance exercise on translational control in human skeletal muscle, we determined the phosphorylation of AMP-activated kinase (AMPK), eukaryotic initiation factor 4E-binding protein (4E-BP1), p70/p85-S6 protein kinase (S6K1), and ribosomal S6 protein (S6). Furthermore, we investigated whether changes in the phosphorylation of S6K1 are muscle fiber type specific. Eight male subjects performed a single high-intensity resistance exercise session. Muscle biopsies were collected before and immediately after exercise and after 30 and 120 min of postexercise recovery. The phosphorylation statuses of AMPK, 4E-BP1, S6K1, and S6 were determined by Western blotting with phospho-specific and pan antibodies. To determine fiber type-specific changes in the phosphorylation status of S6K1, immunofluorescence microscopy was applied. AMPK phosphorylation was increased approximately threefold immediately after resistance exercise, whereas 4E-BP1 phosphorylation was reduced to 27 +/- 6% of preexercise values. Phosphorylation of S6K1 at Thr421/Ser424 was increased 2- to 2.5-fold during recovery but did not induce a significant change in S6 phosphorylation. Phosphorylation of S6K1 was more pronounced in the type II vs. type I muscle fibers. Before exercise, phosphorylated S6K1 was predominantly located in the nuclei. After 2 h of postexercise recovery, phospho-S6K1 was primarily located in the cytosol of type II muscle fibers. We conclude that resistance exercise effectively increases the phosphorylation of S6K1 on Thr421/Ser424, which is not associated with a substantial increase in S6 phosphorylation in a fasted state.

Intramyocellular lipid and glycogen content are reduced following resistance exercise in untrained healthy males

Resistance exercise has recently been shown to improve whole-body insulin sensitivity in healthy males. Whether this is accompanied by an exercise-induced decline in skeletal muscle glycogen and/or lipid content remains to be established. In the present study, we determined fibre-type-specific changes in skeletal muscle substrate content following a single resistance exercise session. After an overnight fast, eight untrained healthy lean males participated in a approximately 45 min resistance exercise session. Muscle biopsies were collected before, following cessation of exercise, and after 30 and 120 min of post-exercise recovery. Subjects remained fasted throughout the test. Conventional light and (immuno)fluorescence microscopy were applied to assess fibre-type-specific changes in intramyocellular triacylglycerol (IMTG) and glycogen content. A significant 27+/-7% net decline in IMTG content was observed in the type I muscle fibres (P<0.05), with no net changes in the type IIa and IIx fibres. Muscle glycogen content decreased with 23+/-6, 40+/-7 and 44+/-7% in the type I, IIa and IIx muscle fibres, respectively (P<0.05). Fibre-type-specific changes in intramyocellular lipid and/or glycogen content correlated well with muscle fibre-type oxidative capacity. During post-exercise recovery, type I muscle fibre lipid content returned to pre-exercise levels within 120 min. No changes in muscle glycogen content were observed during recovery. We conclude that intramyocellular lipid and glycogen stores are readily used during resistance exercise and this is likely associated with the reported increase in whole-body insulin sensitivity following resistance exercise.

Resistance Exercise Does Not Change The Hormonal Response To Subligual Androstenediol Intake

Ingesting androstenediol or androstenedione does not increase serum testosterone concentrations in men, but does elevate serum estradiol concentrations. The elevation in serum estradiol may be exaggerated by resistance exercise. Sublingual administration of androstenediol acutely increases serum testosterone concentrations. However, the effect of resistance exercise on the hormonal response, and the duration of change in serum hormones due to sublingual androstenediol are unknown. PURPOSE This project evaluated the effects of a single session of resistance exercise on the hormonal response to sublingual androstenediol. METHODS Six resistance trained males (22.8 ± 1.0 y, 182.0 ± 3.9 cm, 92.1 ± 2.1 kg, 19.2 ± 3.2% body fat) were administered either sublingual placebo (PL) or 21.4 mg androstenediol (AN) under conditions of a single session of full body resistance exercise consisting of 2 sets of 8–12 repetitions at ∼85% 1-RM (EX) or no exercise (REST). Blood samples were collected before supplementation, at 1, 2, 3, 4, 8, and 12 h post supplementation, with the exercise occurring between h 1 and 2.FigureRESULTS There were no differences in the mass lifted or number of sets or repetitions completed between AN and PL. DISCUSSION These findings indicate that sublingual androstenediol acutely elevates serum testosterone and estradiol concentrations, and that resistance exercise does not alter the increase in serum estradiol or testosterone. These data also indicate that the change in serum hormones due to sublingual androstenediol last less than 8 hours. This project was supported by a Faculty Development Grant from Georgia Southern University.

A single session of resistance exercise enhances insulin sensitivity for at least 24 h in healthy men

The aim of the present study was to determine whether a single session of resistance exercise improves whole-body insulin sensitivity in healthy men for up to 24 h. Twelve male subjects (23 +/- 1 years) were studied over a period of 4 days during which they consumed a standardized diet, providing 0.16 +/- 0.01 MJ.kg(-1).day(-1) containing 15 +/- 0.1 energy% (En%) protein, 29 +/ -0.1 En% fat and 55 +/- 0.3 En% carbohydrate. Insulin sensitivity was determined 24 h before and 24 h after a single resistance exercise session (8 sets of 10 repetitions at 75% of 1 repetition maximum for two leg exercise tasks) using an intravenous insulin tolerance test. Insulin sensitivity index was calculated by the decline in arterial blood glucose concentration following intravenous administration of a single bolus of human insulin (0.075 IU.kg(-1) fat free mass). Basal glucose and insulin concentrations were not changed up to 24 h after the resistance exercise. However, a substantial 13+/-5% improvement in whole-body insulin sensitivity was observed, 24 h after the resistance exercise (P < 0.05). This study shows that even a single session of resistance exercise improves whole-body insulin sensitivity for up to 24 h in healthy men, which is consistent with earlier observations following endurance exercise tasks.

A single session of resistance exercise does not reduce postprandial lipaemia

This study investigated the effect of a single session of resistance exercise on postprandial lipaemia. Eleven healthy normolipidaemic men with a mean age of 23 (standard error = 1.4) years performed two trials at least 1 week apart in a counterbalanced randomized design. In each trial, participants consumed a test meal (1.2 g fat, 1.1 g carbohydrate, 0.2 g protein and 68 kJ · kg−1 body mass) between 08.00 and 09.00 h following a 12 h fast. The afternoon before one trial, the participants performed an 88 min bout of resistance exercise. Before the other trial, the participants were inactive (control trial). Resistance exercise was performed using free weights and included four sets of 10 repetitions of each of 11 exercises. Sets were performed at 80% of 10-repetition maximum with a 2 min work and rest interval. Venous blood samples were obtained in the fasted state and at intervals for 6 h postprandially. Fasting plasma triacylglycerol (TAG) concentration did not differ significantly between control (1.03 ± 0.13 mmol · l−1) and exercise (0.94 ± 0.09 mmol · l−1) trials (mean ± standard error). Similarly, the 6 h total area under the plasma TAG concentration versus time curve did not differ significantly between the control (9.84 ± 1.40 mmol · l−1 · 6 h−1) and exercise (9.38 ± 1.12 mmol · l−1 · 6 h−1) trials. These findings suggest that a single session of resistance exercise does not reduce postprandial lipaemia.

The acute effects of resistance exercise on the main determinants of blood rheology

The aim of this study was to examine short-term changes in blood rheological variables after a single bout of resistance exercise. Twenty-one healthy males completed three sets of 5 – 7 repetitions of six exercises at an intensity corresponding to 80% of one-repetition maximum (1-RM). The average duration of the exercise bout was 35 min. Venous blood samples were obtained before exercise, immediately after exercise and after 30 min of recovery and analysed for lactate, red blood cell count, haematocrit, haemoglobin, plasma viscosity, fibrinogen, total protein and albumin concentration. Plasma volume decreased 10.1% following resistance exercise. This occurred in parallel with an increase of 5.6%, 5.4% and 6.2% in red blood cell count, haemoglobin and haematocrit; respectively. Plasma viscosity increased from 1.55 ± 0.01 to 1.64 ± 0.01 mPa · s immediately after resistance exercise before decreasing to 1.57 ± 0.01 mPa · s at the end of the recovery period. Similarly, fibrinogen, albumin and total protein increased significantly following resistance exercise. However, the rises in all these rheological parameters were transient and returned to pre-exercise values by the end of recovery. We conclude that a single session of heavy resistance exercise performed by normal healthy individuals alters blood rheological variables and that these changes are transient and could be attributed to exercise-induced haemoconcentration.

THE INFLUENCE OF CIRCUIT RESISTANCE TRAINING ON BLOOD LIPID RESPONSES TO CIRCUIT RESISTANCE EXERCISE

While adhering to a physically active lifestyle has been associated with a more favorable lipid profile and a reduced risk of CHD, information regarding the optimal training modality has not been well defined. Resistance training has been recommended as an integral part of a well-rounded physical activity program for health and disease prevention. However, the beneficial influence of this mode of exercise on circulating lipoprotein-lipids remains to be established. PURPOSE To determine the effects of an 8-wk circuit resistance training program on blood lipid responses to a single session of circuit resistance exercise. METHODS Five healthy men and four healthy women underwent three supervised circuit resistance exercise sessions a wk for 8 wks. The average subject age, height, and weight was 22.8 ± 2 yr, 171.7 ± 14 cm, and 73.9 ± 18.5 kg. Serum lipid concentrations were measured before and immediately after exercise (IPE) on two different occasions corresponding to 0 and 8 weeks of training. All IPE serum lipid concentrations were adjusted for changes in plasma volume. RESULTS Circuit resistance training resulted in a 6.5% increase in VO2peak, a 24% increase in upper body strength, and a 29% increase in lower body strength (p < 0.05). Results of a univariate 2 (TRAINING) × 2 (TIME) factorial ANOVA (repeated for both factors) for TC, LDL-C, HDL-C, HDL2-C, HDL3-C, and TG were as follows: TRAINING × TIME interactions were not significant. TRAINING main effects were not significant. For TIME, only TG changes were significant (−4.6%). CONCLUSION Eight weeks of circuit resistance training did not alter the acute response of lipoprotein-lipids to a single session of circuit resistance exercise. TG levels were significantly decreased immediately after a single session of circuit resistance exercise regardless of training status. In addition to improved muscular strength, our results also show that eight weeks of circuit resistance training improves aerobic capacity.

Exercise and growth hormone: Does one affect the other?

The release of growth hormone (GH) is sensitive to many pharmacologic and physiologic stimuli, including exercise. Although the role of the increased amount of GH released during exercise is not fully understood, it most likely contributes to metabolic fuel adaptations during exercise and tissue repair after the exercise session. The GH response to exercise is altered by many factors, including sex steroid concentrations, fitness level, and the intensity of previous exercise sessions. For both endurance and resistance exercise, greater activation of anaerobic glycolysis and lactate formation increases the amount of GH released. Whether an endurance exercise session or an endurance exercise training regimen influences the total amount of GH released during a 24-hour period is not clear; this may depend on the gender of the person, the intensity of the exercise, and the duration of exercise training. The influence of a single session of resistance exercise or resistance training on 24-hour GH secretion has not been studied. Preexercise diet modulation (especially modulation of fat intake) may also influence the release of GH during endurance exercise. Studies that measure the 12- to 24-hour GH response to resistance exercise after the ingestion of various macronutrient diets have not been completed. (J Pediatr 1997;131:S75-80)

Multiaxial fatigue criterion under proportional loading mean strain effect : Golos, K.M. and Osinski, Z. Proc. 4th Int. Conf. on Biaxial/Multiaxial Fatigue II, St. Germain en Laye, France, 31 May–3 June 1994, pp. 303–315

The aim of this study was to compare the acute effects of isometric versus dynamic resistance exercise on pain during a pain-provoking activity, and exercise-induced hypoalgesia in participants with patellar tendinopathy.This study was a pre-registered randomised crossover study. Participants were blinded to the study hypothesis.Participants (N = 21) performed a single session of high load isometric resistance exercise or dynamic resistance exercise, in a randomised order separated by a 7-day washout period. Outcomes were assessed before, immediately after, and 45 min post-exercise. The primary outcome was pain intensity scored on a numeric pain rating scale (NRS; 0–10) during a pain-provoking single leg decline squat (SLDS). Secondary outcomes were pressure pain thresholds (PPTs) locally, distally and remotely, as well as tendon thickness.There was a significant decrease in pain NRS scores (mean reduction 0.9, NRS 95%CI 0.1–1.7; p = 0.028), and increase in PPTs at the tibialis anterior muscle (mean increase 34 kPa 95%CI 9.5–58.5; p = 0.009) immediately post-exercise. These were not sustained 45 min post-exercise for pain (NRS) or PPTs (p > 0.05). There were no differences between exercise on any outcome.While patients with patellar tendinopathy decreased pain during SLDS in response to resistance training, but the magnitude was small. Contraction mode may not be the most important factor in determining the magnitude of pain relieving effects. Similarly, there were only small increases in PPTs at the tibialis anterior which were not superior for isometric exercise.