The effects of continuous and interval training in women and men

Summary Fourteen Subjects (6 male, 8 female) participated in a training program upon a bicycle ergometer for 7 weeks. Group CT followed a continuous training regimen 4 days per week at 70% O₂ max. Group IT trained by an interval method at 100% O₂ max. The duration of each training session was assigned so that each subject would complete 10,000 kpm of work per session during the first week. Each subsequent week, the work load was increased 3000 kpm. Pretraining tests included O₂ max, standard 7 min tests at 80% O₂ and 90% O₂, an endurance test at 90%, and an intense anaerobic work bout at 2400 kpm. Variables assessed were O₂, HR, and blood lactic acid concentrations. The mean increase in O₂ max was 5.1 ml/kg min (15%) for both groups with a corresponding increase in maximal lactate of 20 mg-%. The response to the post-training tests was nearly identical for both groups: submaximal heart rate at the same absolute work load declined 17 beats/min (CT) and 15 beats/min (IT), submaximal lactate levels declined significantly, endurance ride duration increased 26 min. Continuous and interval training at 70% and 100% O₂ max respectively produce identical changes in heart rate response, blood lactic acid concentration and O₂ max when the total work load is equated per training session.     

The effects of low-intensity resistance training with vascular restriction on leg muscle strength in older men

The purpose of this study was to investigate and compare the effects of two types of resistance training protocols on the adaptation of skeletal muscle strength in older men. Thirty-seven healthy male subjects (50–64 years) participated in this study. Subjects were assigned to one of three groups: high-intensity (80% 1-RM) resistance training (RT80); low-intensity (20% 1-RM) resistance training with vascular restriction (VR-RT20); and a control group (CON) that performed no exercise. Subjects in both exercise groups performed three upper body (at 80% 1-RM) and two lower body exercises either with (20% 1-RM) or without (80% 1-RM) vascular restriction three times a week for 6 weeks. As expected, the RT80 and VR-RT20 groups had significantly (p < 0.01) greater strength increases in all upper body and leg press exercises compared with CON, however, absolute strength gains for the RT80 and VR-RT20 groups were similar (p > 0.05). It should be noted that the percentage increase in leg extension strength for the RT80 group was significantly greater than that for both the VR-RT20 (p < 0.05) and CON groups (p < 0.01), while the percentage increase in leg extension strength for the VR-RT20 group was significantly (p < 0.01) greater than that for the CON. The findings suggested that leg muscle strength improves with the low-load vascular restriction training and the VR-RT20 training protocol was almost as effective as the RT80 training protocol for increasing muscular strength in older men.     

The effects of creatine supplementation on muscular performance and body composition responses to short-term resistance training overreaching

To determine the effects of creatine supplementation during short-term resistance training overreaching on performance, body composition, and resting hormone concentrations, 17 men were randomly assigned to supplement with 0.3 g/kg per day of creatine monohydrate (CrM: n=9) or placebo (P: n=8) while performing resistance exercise (5 days/week for 4 weeks) followed by a 2-week taper phase. Maximal squat and bench press and explosive power in the bench press were reduced during the initial weeks of training in P but not CrM. Explosive power in the bench press, body mass, and lean body mass (LBM) in the legs were augmented to a greater extent in CrM (P0.05) by the end of the 6-week period. A tendency for greater 1-RM squat improvement (P=0.09) was also observed in CrM. Total testosterone (TT) and the free androgen index (TT/SHBG) decreased in CrM and P, reaching a nadir at week 3, whereas sex hormone binding globulin (SHBG) responded in an opposite direction. Cortisol significantly increased after week 1 in CrM (+29%), and returned to baseline at week 2. Insulin was significantly depressed at week 1 (–24%) and drifted back toward baseline during weeks 2–4. Growth hormone and IGF-I levels were not affected. Therefore, some measures of muscular performance and body composition are enhanced to a greater extent following the rebound phase of short-term resistance training overreaching with creatine supplementation and these changes are not related to changes in circulating hormone concentrations obtained in the resting, postabsorptive state. In addition, creatine supplementation appears to be effective for maintaining muscular performance during the initial phase of high-volume resistance training overreaching that otherwise results in small performance decrements.     

Whole-body vibration augments resistance training effects on body composition in postmenopausal women

Age-related changes in body composition are well-documented with a decrease in lean body mass and a redistribution of body fat generally observed. Resistance training alone has been shown to have positive effects on body composition, however, these benefits may be enhanced by the addition of a vibration stimulus.     

The effect of resistance training on blood pressure in normotensive women

The purpose of the present study was to determine whether conventional resistance training alters 24-h ambulatory and manually determined casual blood pressure of normotensive women. Seven individuals (23 +/- 2 years old) trained 2 days week-1 for 20 weeks emphasizing the hip and knee extensor muscle groups. Three sets to exhaustion of the knee extension, squat, knee flexion and leg press exercises were performed. The load for each exercise represented approximately 80-85% of the one-repetition maximum. Average values for 24-h ambulatory blood pressure were not different (P greater than 0.05) pre- and post-training (systolic, 107 +/- 4 vs. 109 +/- 1 mmHg; diastolic, 73 +/- 2 vs. 71 +/- 2 mmHg). Ambulatory values over 8-h segments of the 24 h (day, evening, night) and casual resting determinations of blood pressure were also not affected. The lack of change in blood pressure cannot be explained by an insufficient training response. Knee extensor strength during dynamic or isokinetic actions increased (approximately 43%, P less than 0.05). In addition, biopsies from the vastus lateralis muscle showed an increase (P less than 0.05) in average muscle fibre cross-sectional area of 32%. This hypertrophic response was further substantiated by an increase (P less than 0.05) in lean body mass (41.2 +/- 1.3 kg to 43.4 +/- 1.5 kg). These results indicate that resistance training, which increases muscular strength, muscle fibre area and lean body mass, does not alter ambulatory or casual blood pressure. Thus, the concern that conventional resistance training may chronically elevate blood pressure does not appear warranted, at least in normotensive women.     

The effects of long-term low intensity aerobic training and detraining on serum lipid and lipoprotein concentrations in elderly men and women

The effects of long-term low intensity aerobic training and detraining on serum lipid and lipoprotein concentrations were examined in 30 elderly men and women. These subjects were randomly divided into two groups. The training group [n=15; 7 men and 8 women; mean age 75.5 (SD 5.6) years] agreed to take part in physical training using a treadmill with an exercise intensity at the blood lactate concentration threshold for 30 min 3–6 times a week for 9 months. The other group [n=15; 7 men and 8 women; mean age 73.7 (SD 4.4) years] did not perform any particular physical training and was followed as the control. Following this training period the high density lipoprotein-cholesterol (HDL-C) had increased significantly (P<0.01) while the total cholesterol (TC) : HDL-C ratio had decreased significantly (P<0.01) in the training group after 9 months but had not changed in the control group. The TC, triglyceride (TG) and low density lipoprotein-cholesterol (LDL-C) had not changed significantly in either group. No significant difference was seen between the groups throughout the period for TC, LDLC or TG. There was, however, a significant correlation between the initial TC:HDL-C ratio and the change in the TC:HDL-C ratio following 3 months of training (P <0.05). After 1 month of detraining in 5 patients, the HDL-C had decreased significantly (P < 0.05) while the TC:HDL-C had increased significantly in the training group (P<0.01). These results suggested that long-term low intensity aerobic training improved the profile of serum lipid and lipoprotein concentrations, while detraining returned the profile to that of the pretraining levels in elderly persons.     

Two years of resistance training in older men and women: the effects of three years of detraining on the retention of dynamic strength.

Dynamic muscle strength (1-RM) and symptom-limited treadmill endurance were compared among three groups (5 M and 5 F per group) of older adults (mean age 72.5 yrs) who had either weight-trained continuously twice per week for 5 years (Tr), ceased to weight train after 2 years (Detr), or acted as controls throughout (Con). The Tr and Detr trained hard (progressing up to 3 sets at up to 80% of 1-RM) for 2 years; the Tr continued training for an additional 3 years at a maintenance level (2 to 3 sets at 60-70% 1-RM), whereas the Detr stopped training for those 3 years. The Con subjects did not train for the duration of the study but took part in identical testing procedures. After 2 years of resistance training, dynamic strength in the Tr and Detr groups increased significantly above baseline and Con values for all exercises, p < 0.0001. Following 3 years of maintenance level training, arm curl, leg press, and bench press 1-RM (sum of both limbs) in the Tr remained significantly above baseline values (21.6 kg = 17%; 15.7 kg = 82%; 8.3 kg = 34%, respectively). The 1-RM in Detr were 18.4 kg (14%), 5.3 kg (24%), and 1.4 kg (9%) above baseline for leg press, arm curl, and bench press after 5 years, whereas the Con declined over the 5-yr period by 18.4 kg (-9.7%), 4.4 kg (-19%), and 3.5 kg (-6%), respectively. There were nonsignificant improvements in treadmill performance in the Tr and Detr, and a decline in the Con after 2 years. Treadmill performance declined between Years 2 and 5 in all groups despite continued training (ns). We conclude that: (1) dynamic strength gains from 2 years of resistance training in older individuals are not entirely lost even after 3 years of detering; (2) these effects may be specific to the exercises performed in the training program; (3) adoption of maintenance-level moderate-intensity training significantly attenuates the decline in dynamic strength of previously trained muscles.     

Effects of high-intensity resistance training and low-intensity resistance training with vascular restriction on bone markers in older men

The aim of this study was to examine and compare the effects of different resistance training protocols on bone marker concentrations in older men. Thirty-seven healthy older male subjects were assigned to one of three groups: high-intensity resistance training (HI-RT, age?=?57.5?±?0.8); low-intensity resistance training with vascular restriction (LI-VRT, age?=?59.9?±?1.0); and control (CON, age?=?57.0?±?1.1). Blood samples were collected before and after 6?weeks of resistance training to measure the changes in bone formation [bone alkaline phosphatase, (Bone ALP)] and resorption (C-terminal cross-linking telopeptide of Type-I collagen, CTX) marker concentrations. A significant main effect for time was detected in Bone ALP to CTX ratio for the exercise groups (p??LI-VRT, p?相似文献   

The effect of short-term aerobic training on coagulation and fibrinolytic factors in sedentary healthy postmenopausal women

Objective

The purpose of this study was to assess the effect of short-term aerobic training on the fibrinolytic and coagulative factors in postmenopausal women.

Study design

Twenty volunteer sedentary healthy postmenopausal women (48–53 years), who entered the menopause naturally, were divided randomly into two groups: training (n = 10) and control (n = 10).

Methods and main outcome measures

Training consisted of 10 sessions of submaximal aerobic cycling, 35 min for each session (5 min warm-up, 25 min aerobic training with 70% HRmax, 5 min active and 15 min passive recovery), 3 times a week. Coagulation and fibrinolytic factors were assessed both before and after aerobic program in both groups.

Results

Fibrinogen, von Willbrand factor (vWF-Ag) antigen, plasminogen activator inhibitor-1 activity (PAI-1:Ac) and antigen (PAI-1:Ag) showed significant reduction after 10 sessions in the training group (P < 0.05). Also after training, prothrombin time (PT), partial thromboplastin time (PTT), tissue plasminogen activator activity (tPA:Ac) and antigen (tPA:Ag) increased (P < 0.05).

Conclusion

It was concluded that fibrinolytic activity on postmenopausal women could be improved by a 3-week regular submaximal training program. These changes on the hemostatic factors suggest that short-term aerobic training may prevent the decline in fibrinolytic function observed in sedentary postmenopausal women.     

The effects of long-term simulated microgravity on neuromuscular performance in men and women

The effects are reported of prolonged exposure to simulated microgravity (strict bed rest in an antiorthostatic position –?6° head-down tilt, HDT) on voluntary and electrically evoked contractions of the triceps surae muscle in men (n?=?6) and women (n?=?4). The subjects served as their own controls. Bed rest is a model that has commonly been used to simulate spaceflight. Measurements made in the control condition (10–8 days before the beginning of HDT) and after 120-days of HDT (on the 3rd day after it ended) included examination of the properties of isometric maximal voluntary contractions (MVC), isometric twitch contractions (P_t) and tetanic contractions (P_o). After HDT, the MVC decreased by means of 44% and 33%, P_t by means of 36% and 11%, P_o by means of 34% and 24%, in the men and the women, respectively. The difference between P_o and MVC, expressed as a percentage of P_o and referred to as force deficiency (FD), has also been calculated. The FD increased by means of 60% and 28.8% in the men and the women, respectively. Time-to-peak tension of the triceps surae muscle increased by means of 12% and 14% in the men and the women, respectively, but half-relaxation time decreased by means of 9% and 19%. Total contraction time increased by a mean of 23% in the men and decreased by a mean of 17% in the women. Force-velocity of properties of the triceps surae muscle calculated according to a relative scale of voluntary contraction development significantly decreased more in the women than the men. The calculations of the same properties of electrically evoked contraction development did not differ substantially from the initial physiological state. It can be concluded that not only were the contractile properties of the triceps surae muscle significantly different in the men and the women, but that the effects of exposure to simulated microgravity on these properties were also different. These differences may be explained by sex differences in the muscle tissue itself and in its maximal neural activition.     

Effect of combined resistance and aerobic training on reactive hyperemia in men

Reduced response to reactive hyperemia (RH) in the extremities reflects impaired endothelium-dependent vasodilation of the microvasculature. The aims of the present study were to determine whether resistance training and a combination of aerobic and resistance training increase the endothelial vasodilation of the forearm assessed by RH. A total of 39 young men were assigned to either high-intensity resistance training (HIR; six types of exercises, 80% 1RM × 10 repetitions × 3 sets, n = 14) or moderate-intensity resistance training (MIR; six types of exercises, 50% 1RM × 16 repetitions × 3 sets, n = 14) or a combination of high-intensity resistance training and moderate-intensity endurance training (COMBO; HIR and 60% maximal heart rate × 30 min, n = 11) groups. We measured forearm blood flow response to RH before and after 4 months of exercise intervention. All training groups increased maximal strength in all muscle groups tested (all P < 0.05). After 4 months of training, the forearm blood flow during RH increased significantly in the MIR and COMBO groups, from 57 ± 4 to 66 ± 7 ml/min per 100 ml tissue and from 59 ± 6 to 74 ± 8 ml/min per 100 ml tissue, respectively (both P < 0.05). There was no change in the response to RH in the HIR groups. In conclusion, the findings in this study demonstrate that combined resistance and aerobic training may affect the vasoreactivity response to RH in the forearm, but not resistance training alone.     

Effects of resistance training on resting immune parameters in women

The aim of this investigation was to determine whether intense resistance training of 6 months duration influenced resting immune parameters. Previously untrained women underwent one of four training programs or were non-training controls (CON, n=7). The resistance-training groups trained for total body power (TP, n=16), total body hypertrophy (TH, n=18), upper body power (UP, n=15) or upper body hypertrophy (UH, n=15). Immune parameters were measured from a fasting morning blood draw in September/October (0 months, t ₀), November/December (3 months, t ₃), and April/May (6 months, t ₆). Lymphocyte subsets [CD4+ T cells, CD8+ T cells, natural killer cells (NK), and B cells], and mitogen-stimulated proliferation were measured. The concentration of NK cells increased (P<0.001) after 3 months of training for the resistance-training groups but not the CON group. This increase was not present after 6 months of training, thus it was a transient change. Lymphocyte proliferation responses were similar across time for the resistance-trained and CON groups for all stimulation conditions. Thus, resistance training induces a transient increase in NK cells but has little effect on lymphocyte trafficking or proliferation. This was consistent despite differences in the volume of muscle mass trained or the manner of training (power verses hypertrophy). Electronic Publication     

Protein supplementation before and after resistance training in older men

We determined the effects of protein supplementation immediately before (PRO-B) and after (PRO-A) resistance training (RT; 12 weeks) in older men (59–76 years), and whether this reduces deficits in muscle mass and strength compared to younger men (18–40 years). Older men were randomized to PRO-B (0.3 g/kg protein before RT + placebo after RT, n=9), PRO-A (placebo before + protein after RT, n=10), or PLA (placebo before and after RT, n=10). Lean tissue mass, muscle thickness of the elbow, knee, and ankle flexors and extensors, and leg and bench press strength were measured before and after RT and compared to databases of younger subjects (n=22–60). Myofibrillar protein degradation (3-methylhistidine) and bone resorption (cross-linked N-telopeptides) were also measured before and after RT. Lean tissue mass, muscle thickness (except ankle dorsi flexors), and strength increased with training (P<0.05), with little difference between groups. There were no changes in 3-methylhistidine or cross-linked N-telopeptides. Before RT, all measures were lower in the older compared to younger groups (P<0.05), except for elbow extensor muscle thickness. Following training, muscle thickness of the elbow flexors and ankle dorsi flexors and leg press strength were no longer different than the young, and elbow extensor muscle thickness was greater in the old men (P<0.05). Supplementation with protein before or after training has no effect on muscle mass and strength in older men. RT was sufficient to overcome deficits in muscle size of the elbow flexors and ankle dorsi flexors and leg press strength in older compared to younger men.     

Effects of short-term endurance exercise training on vascular function in young males

We investigated effects of 6 days of endurance exercise training [cycling at 65% of peak oxygen consumption (VO_2peak) for 2 h a day on six consecutive days] on vascular function in young males. Measures of VO_2peak, arterial stiffness, calf vascular conductance and heart rate variability were obtained pre- and post-training. Indices of arterial stiffness were obtained by applanation tonometry to determine aortic augmentation index normalized to a heart rate of 75 bpm (AI _x @75 bpm), and central and peripheral pulse wave velocity (CPWV, PPWV). Resting and maximal calf vascular conductances were calculated from concurrent measures of blood pressure and calf blood flow using venous occlusion strain-gauge plethysmography. Time and frequency domain measures of heart rate variability were obtained from recording R–R intervals during supine and standing conditions. Both CPWV (5.9 ± 0.8 vs. 5.4 ± 0.8 m/s) and PPWV (9.7 ± 0.8 vs. 8.9 ± 1.3 m/s) were reduced following the training program. No significant changes were observed in AI _x @75 bpm, vascular conductance, heart rate variability or VO_2peak. These data indicate that changes in arterial stiffness independent of changes in heart rate variability or vascular conductance can be achieved in healthy young males following only 6 days of intense endurance exercise.     

Time course for strength and muscle thickness changes following upper and lower body resistance training in men and women

 The purpose of this study was to investigate the time course of skeletal muscle adaptations resulting from high-intensity, upper and lower body dynamic resistance training (WT). A group of 17 men and 20 women were recruited for WT, and 6 men and 7 women served as a control group. The WT group performed six dynamic resistance exercises to fatigue using 8–12 repetition maximum (RM). The subjects trained 3 days a week for 12 weeks. One-RM knee extension (KE) and chest press (CP) exercises were measured at baseline and at weeks 2, 4, 6, 8, and 12 for the WT group. Muscle thickness (MTH) was measured by ultrasound at eight anatomical sites. One-RM CP and KE strength had increased significantly at week 4 for the female WT group. For the men in the WT group, 1 RM had increased significantly at week 2 for KE and at week 6 for CP. The mean relative increases in KE and CP strength were 19% and 19% for the men and 19% and 27% for the women, respectively, after 12 weeks of WT. Resistance training elicited a significant increase in MTH of the chest and triceps muscles at week 6 in both sexes. There were non-significant trends for increases in quadriceps MTH for the WT groups. The relative increases in upper and lower body MTH were 12%–21% and 7%–9% in the men and 10%–31% and 7%–8% in the women respectively, after 12 weeks of WT. These results would suggest that increases in MTH in the upper body are greater and occur earlier compared to the lower extremity, during the first 12 weeks of a total body WT programme. The time-course and proportions of the increase in strength and MTH were similar for both the men and the women. Accepted: 6 September 1999     

Plasma catecholamine responses and neural adaptation during short-term resistance training

Low exercise-induced plasma adrenaline (A) responses have been reported in resistance-trained individuals. In the study reported here, we investigated the interaction between strength gain and neural adaptation of the muscles, and the plasma A response in eight healthy men during a short-term resistance-training period. The subjects performed 5 resistance exercises (E1–E5), consisting of 6 sets of 12 bilateral leg extensions performed at a 50% load, and with 2 days rest in between. Average electromyographic (EMG) signal amplitude was recorded before and after the exercises, from the knee extensor muscles in isometric maximal voluntary contraction (MVC) as well as during the exercises (aEMG_max and aEMG_exerc, respectively). Total oxygen consumed during the exercises (V˙O_2tot) was also measured. All of the exercises were exhaustive and caused significant decreases in MVC (34–36%, P < 0.001). As expected, the concentric one-repetition maximum (1-RM), MVC and aEMG_max were all higher before the last exercise (E5) than before the first exercise (E1; 7, 9 and 19%, respectively, P < 0.05). In addition, in E5 the aEMG_exerc:load and V˙O_2tot:load ratios were lower than in E1 (−5 and −14%, P < 0.05), indicating enhanced efficiency of the muscle contractions, However, the post-exercise plasma noradrenaline (NA) and A were not different in these two exercises [mean (SD) 10.2 (3.8) nmol · l⁻¹ vs 11.3 (6.0) nmol · l⁻¹, ns, and 1.2 (1.0) nmol · l⁻¹ vs 1.9 (1.1) nmol · l⁻¹, ns, respectively]. However, although NA increased similarly in every exercise (P < 0.01), the increase in A reached the level of statistical significance only in E1 (P < 0.05). The post-exercise A was also already lower in E2 [0.7 (0.7) nmol · l⁻¹, P < 0.05) than in E1, despite the higher post-exercise blood lactate concentration than in the other exercises [9.4 (1.1) mmol · l⁻¹, P < 0.05]. Thus, the results suggest that the observed attenuation in the A response can not be explained by reduced exercise-induced strain due to the strength gain and neural adaptation of the muscles. Correlation analysis actually revealed that those individuals who had the highest strength gain during the training period even tended to have an increased post-exercise A concentration in the last exercise as compared to first one (r=0.76, P < 0.05). Accepted: 10 February 2000     

Increase in calf post-occlusive blood flow and strength following short-term resistance exercise training with blood flow restriction in young women

The response of calf muscle strength, resting (R _bf) and post-occlusive (PO_bf) blood flow were investigated following 4 weeks resistance training with and without blood flow restriction in a matched leg design. Sixteen untrained females performed unilateral plantar-flexion low-load resistance training (LLRT) at either 25% (n = 8) or 50% (n = 8) one-repetition maximum (1 RM). One limb was trained with unrestricted blood flow whilst in the other limb blood flow was restricted with the use of a pressure applied cuff above the knee (110 mmHg). Regardless of the training load, peak PO_bf, measured using venous occlusion plethysmography increased when LLRT was performed with blood flow restriction compared to no change following LLRT with unrestricted blood flow. A significant increase (P < 0.05) in the area under the blood time–flow curve was also observed following LLRT with blood flow restriction when compared LLRT with unrestricted blood flow. No changes were observed in R _bf between groups following training. Maximal dynamic strength (1 RM), maximal voluntary contraction and isokinetic strength at 0.52 and 1.05 rad s⁻¹ also increased (P < 0.05) by a greater extent following resistance training with blood flow restriction. Moreover, 1 RM increased to a greater extent following training at 50% 1 RM compared to 25% 1 RM. These results suggest that 4 weeks LLRT with blood flow restriction provides a greater stimulus to increase peak PO_bf as well as strength parameters than LLRT with unrestricted blood flow.