Biomedical subjects

K Häkkinen

Publications and source records attributed to K Häkkinen.

At least 19 recordsLinked to original sources

PubMed2006

Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.

OBJECTIVE: To evaluate the short- and long-term efficacy of exercise therapy in a warm, waist-high pool in women with fibromyalgia. METHODS: Thirty-four women (mean +/- SD tender points 17 +/- 1) were randomly assigned to either an exercise group (n = 17) to perform 3 weekly sessions of training including aerobic, proprioceptive, and strengthening exercises during 12 weeks, or to a control group (n = 17). Maximal unilateral isokinetic strength was measured in the knee extensors and flexors in concentric and eccentric actions at 60 degrees /second and 210 degrees /second, and in the shoulder abductors and adductors in concentric contractions. Health-related quality of life (HRQOL) was assessed using the EQ-5D questionnaire; pain was assessed on a visual analog scale. All were measured at baseline, posttreatment, and after 6 months. RESULTS: The strength of the knee extensors in concentric actions increased by 20% in both limbs after the training period, and these improvements were maintained after the de-training period in the exercise group. The strength of other muscle actions measured did not change. HRQOL improved by 93% (P = 0.007) and pain was reduced by 29% (P = 0.012) in the exercise group during the training, but pain returned close to the pretraining level during the subsequent de-training. However, there were no changes in the control group during the entire period. CONCLUSION: The therapy relieved pain and improved HRQOL and muscle strength in the lower limbs at low velocity in patients with initial low muscle strength and high number of tender points. Most of these improvements were maintained long term.

Adult↗

PubMed2006

Effect of loading on unintentional lifting velocity declines during single sets of repetitions to failure during upper and lower extremity muscle actions.

The purpose of this study was to examine the effect of different loads on repetition speed during single sets of repetitions to failure in bench press and parallel squat. Thirty-six physical active men performed 1-repetition maximum in a bench press (1 RM (BP)) and half squat position (1 RM (HS)), and performed maximal power-output continuous repetition sets randomly every 10 days until failure with a submaximal load (60 %, 65 %, 70 %, and 75 % of 1RM, respectively) during bench press and parallel squat. Average velocity of each repetition was recorded by linking a rotary encoder to the end part of the bar. The values of 1 RM (BP) and 1 RM (HS) were 91 +/- 17 and 200 +/- 20 kg, respectively. The number of repetitions performed for a given percentage of 1RM was significantly higher (p < 0.001) in half squat than in bench press performance. Average repetition velocity decreased at a greater rate in bench press than in parallel squat. The significant reductions observed in the average repetition velocity (expressed as a percentage of the average velocity achieved during the initial repetition) were observed at higher percentage of the total number of repetitions performed in parallel squat (48 - 69 %) than in bench press (34 - 40 %) actions. The major finding in this study was that, for a given muscle action (bench press or parallel squat), the pattern of reduction in the relative average velocity achieved during each repetition and the relative number of repetitions performed was the same for all percentages of 1RM tested. However, relative average velocity decreased at a greater rate in bench press than in parallel squat performance. This would indicate that in bench press the significant reductions observed in the average repetition velocity occurred when the number of repetitions was over one third (34 %) of the total number of repetitions performed, whereas in parallel squat it was nearly one half (48 %). Conceptually, this would indicate that for a given exercise (bench press or squat) and percentage of maximal dynamic strength (1RM), the pattern of velocity decrease can be predicted over a set of repetitions, so that a minimum repetition threshold to ensure maximal speed performance is determined.

Adult↗

PubMed2004

Relationship between diet and serum anabolic hormone responses to heavy-resistance exercise in men.

Relationship between dietary intake and serum anabolic hormone concentrations of testosterone (T), free testosterone (FT), and growth hormone were examined at rest as well as after the heavy-resistance exercise (HRE) in 8 strength athletes (SA) and 10 physically active non-athletes (NA). In the first part of the study serum basal anabolic hormone concentrations and dietary intake were examined in the total group of subjects. In the second part of the study a subgroup of 5 SA and 5 NA performed the high volume and high intensity HRE. Dietary intake was registered by dietary diaries for 4 days preceding the loading day. Significant correlations were observed between serum basal T and fat (E%: r = 0.55, p < 0.05, g/kg: r = 0.65, p < 0.01) and protein intake (E%: r = - 0.77, p < 0.001, g/kg: r = - 0.68, p < 0.01) in the total group of subjects. However, when the two groups were examined separately the significant relationships between serum basal T and dietary fat and protein could be noticed in SA only (fat g/kg: SA r = 0.77, p < 0.05; in NA r = 0.44, n.s., protein g/kg: SA r = - 0.84, p < 0.05; in NA r = 0.27, n.s.). Both serum T and FT responses to HRE were correlated with fat (E%: r = 0.85, p < 0.01 and r = 0.73, p < 0.05, g/kg: r = 0.72, p < 0.05 and r = 0.77, p < 0.01) and protein (E%: r = - 0.81, p < 0.01 and r = - 0.69, p < 0.05, g/kg: r = - 0.86, p < 0.01 and r = - 0.65, p < 0.05). The results suggest the possible role of diet leading to alterations in serum T and FT during prolonged strength training, and that diets with insufficient fat and/or excessive protein may compromise the anabolic hormonal environment over a training program.

Adult↗

PubMed2003

Effects of concurrent strength and endurance training in women with early or longstanding rheumatoid arthritis: comparison with healthy subjects.

OBJECTIVE: To investigate the effects of a 21-week concurrent strength and endurance training protocol on physical fitness profile in women with early or longstanding rheumatoid arthritis (RA) compared with healthy subjects. METHODS: Twenty-three female patients with RA volunteered for the study. Twelve had early RA and eleven had longstanding RA. Twelve healthy women served as controls. Maximal strength of different muscle groups was measured by dynamometers, walking speed with light cells, and vertical squat jump on the force platform to mirror explosive force. Maximal oxygen uptake was measured by gas analyzer. Six training sessions (3 strength training and 3 endurance training) were carried out in a 2-week period for 21 weeks. RESULTS: The training led to large gains in maximal strength both in women with RA and in healthy women (P < 0.043-0.001). The strength gains were accompanied by increases in walking speed (P < 0.034-0.001) and vertical squat jump (P < 0.034-0.001). Significant improvements also occurred in maximal aerobic capacity in all groups (P < 0.023-0.014). CONCLUSIONS: Both early and longstanding RA patients with stable disease can safely improve all characteristics of their physical fitness profile using a progressive concurrent strength and endurance training protocol.

Adult↗

PubMed2003

Changes in knee extension and flexion force, EMG and functional capacity during strength training in older females with fibromyalgia and healthy controls.

OBJECTIVE: To investigate the effects of strength training on neuromuscular functions in elderly females with fibromyalgia (FM). METHODS: Thirteen females with fibromyalgia [group FMt; mean age (s.d.) 60.2 (2.5) years] and 11 healthy controls [group HCt; 64.2 (2.7) yr] carried out supervised strength training twice a week for 21 weeks. Thirteen FM patients [group FMc; 59.1 (3.5) yr] served as non-training controls. Maximal isometric force and electromyographic (EMG) activity of the right quadriceps femoris in knee extension and flexion actions, maximal 10-m walking speed, and 10-step stair-climbing time were measured. Tender points were assessed by palpation, subjectively perceived symptoms with a visual analogue scale, and the self-reported physical function capacity by Health Assessment Questionnaire (HAQ). RESULTS: The mean (s.d.) increases in maximal extension force during the training period in groups FMt and in HCt were 32 (33)% (P < 0.001) and 24 (12)% (P < 0.001) respectively and those of flexion were 13 (20)% (P < 0.05) and 24 (17)% (P < 0.01). Explosive force of the extensors increased in both FMt and in HCt. The integrated EMGs of the vastus lateralis and medialis muscles increased in both FMt and HCt. Muscle forces and EMGs in group FMc remained at the basal level. Walking speed, stair-climbing time and the HAQ index improved in group FMt. The changes in the number of tender points and in perceived symptoms were in favour of the training group FMt. CONCLUSIONS: The data support the hypothesis that elderly female FM patients have normal neuromuscular function. Supervised strength training also suits elderly FM patients, has positive effects on perceived symptoms and improves functional capacity without complications.

Aged↗

PubMed2003

Influence of muscle strength and total work on exercise-induced plasma growth hormone isoforms in women.

The purpose of this investigation was to determine the influence of physical strength and the ability to do more total work on human growth hormone (GH) variants to a heavy resistance exercise protocol in untrained women. From a distribution of 100 healthy, untrained women, the strongest 10 women (S) and the weakest 10 women (W) were compared for GH responses pre- and post an acute heavy resistance exercise test (AHRET, 6 sets of 10 RM squats, 2 minutes rest between sets). Blood samples were obtained pre-exercise and immediately post-exercise and subsequently analysed in total as well as fractionated by Sephacryl S-100R column chromatography into three molecular weight size classes: fraction A: > 60 kD, fraction B: 30-60 kD, fraction C: < 30 kD. For each total sample as well as each fraction, immunoreactive GH was measured via the Nichols IRMA, while bioactive GH was measured via the hypox rat tibial line bioassay and Diagnostic Systems Laboratory's immunofunctional GH ELISA. No exercise-induced changes or differences between groups were observed in the tibial line bioassay. However, the S group displayed a significantly higher pre-exercise resting value in the total fraction than the W group. Conversely, the W group exhibited a significantly higher pre-exercise value in the smaller molecular weight fraction C. With regards to the immunofunctional and immunoreactive assays, the total fraction, fraction A, and fraction B demonstrated significant (P < or = 0.05) exercise-induced increases in both the S and W group despite no group differences. For the Nichols and immunofunctional assays significant exercise-induced changes were observed in the smaller molecular weight C fraction in the W group but not the S group. However, the S group displayed a significantly higher pre-exercise value in fraction C relative to the W group. These data demonstrate for the first time that differences exist in the GH molecular weight variants between strong and weak untrained women, with the lower molecular weight variants seemingly less responsive to greater amounts of exercise in stronger women, thus suggesting differential regulation of GH molecular weight variants during resistance exercise due to pre-existing physical parameters.

Animals↗

PubMed2003

Acute hormonal and neuromuscular responses and recovery to forced vs maximum repetitions multiple resistance exercises.

Acute hormonal and neuromuscular responses and recovery three days after the exercises were examined during the maximum repetitions (MR) and forced repetitions (FR) resistance exercise protocols in 16 male athletes. MR included 4 sets of leg presses, 2 sets of squats and 2 sets of knee extensions (with 12 RM) with a 2-min recovery between the sets and 4 min between the exercises. In FR the initial load was chosen to be higher than in MR so that the subject could not lift 12 repetitions per set by himself. After each set to failure the subject was assisted to perform the remaining repetitions to complete the 12 repetitions per set. Thus the exercise intensity was greater in FR than in MR. Both loading protocols led to the great acute increases (p < 0.05 - 0.001) in serum testosterone, free testosterone, cortisol and GH concentrations. However, the responses in cortisol (p < 0.05) and GH (p < 0.01) were larger in FR than in MR. The decrease of 56.5 % (p < 0.001) in maximal isometric force in FR was greater (p < 0.001) than that of 38.3 % in MR (p < 0.001) and force remained lower (p < 0.01) during the recovery in FR compared to MR. The larger decrease in isometric strength in FR than in MR was also associated with the decreased maximal voluntary EMG of the loaded muscles. The data indicate that the forced repetition exercise system induced greater acute hormonal and neuromuscular responses than a traditional maximum repetition exercise system and therefore it may be used to manipulate acute resistance exercise variables in athletes.

Electromyography↗

PubMed2002

Neuromuscular adaptations during concurrent strength and endurance training versus strength training.

The purpose of this study was to investigate effects of concurrent strength and endurance training (SE) (2 plus 2 days a week) versus strength training only (S) (2 days a week) in men [SE: n=11; 38 (5) years, S: n=16; 37 (5) years] over a training period of 21 weeks. The resistance training program addressed both maximal and explosive strength components. EMG, maximal isometric force, 1 RM strength, and rate of force development (RFD) of the leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF) throughout the lengths of 4/15-12/15 (L(f)) of the femur, muscle fibre proportion and areas of types I, IIa, and IIb of the vastus lateralis (VL), and maximal oxygen uptake (VO(2max)) were evaluated. No changes occurred in strength during the 1-week control period, while after the 21-week training period increases of 21% (p<0.001) and 22% (p<0.001), and of 22% (p<0.001) and 21% (p<0.001) took place in the 1RM load and maximal isometric force in S and SE, respectively. Increases of 26% (p<0.05) and 29% (p<0.001) occurred in the maximum iEMG of the VL in S and SE, respectively. The CSA of the QF increased throughout the length of the QF (from 4/15 to 12/15 L(f)) both in S (p<0.05-0.001) and SE (p<0.01-0.001). The mean fibre areas of types I, IIa and IIb increased after the training both in S (p<0.05 and 0.01) and SE (p<0.05 and p<0.01). S showed an increase in RFD (p<0.01), while no change occurred in SE. The average iEMG of the VL during the first 500 ms of the rapid isometric action increased (p<0.05-0.001) only in S. VO(2max) increased by 18.5% (p<0.001) in SE. The present data do not support the concept of the universal nature of the interference effect in strength development and muscle hypertrophy when strength training is performed concurrently with endurance training, and the training volume is diluted by a longer period of time with a low frequency of training. However, the present results suggest that even the low-frequency concurrent strength and endurance training leads to interference in explosive strength development mediated in part by the limitations of rapid voluntary neural activation of the trained muscles.

Adaptation, Physiological↗

PubMed2001

Differential effects of exhaustive cycle ergometry on concentric and eccentric torque production.

The purpose of this study was to investigate the potential differences in peak isokinetic concentric end eccentric torque following low- and high-intensity cycle exercise fatigue protocols. Ten healthy, recreationally-active men were tested in a balanced, randomized testing sequence for peak eccentric and concentric isokinetic torque (60 degrees/sec) immediately before and after three experimental conditions each separated by 48 hours: 1) a bout of high intensity cycling consisting of a maximal 90-second sprint; 2) a bout of low-intensity cycling at 60 rpm equated for total work with the high-intensity protocol: and 3) no exercise (control bout). Blood was drawn from an antecubital vein and plasma lactate concentrations were determined immediately before and after each experimental bout. Post-exercise plasma lactate concentrations were 15.1 +/- 2.5 and 4.7 +/- 1.9 mmol l(-1), respectively, following the high- and low-intensity protocols. The high intensity exercise bout resulted in the only post-exercise decrease in concentric and eccentric isokinetic peak torque. The percent decline in maximal force production was significantly (P< 0.05) greater for concentric muscle actions compared to eccentric (29 vs 15%, respectively). In conclusion, a 90-second maximal cycling sprint results in a significant decline in maximal torque of both concentric and eccentric muscle actions with the greatest magnitude observed during concentric muscle actions.

Adult↗

PubMed2001

Changes in electromyographic activity, muscle fibre and force production characteristics during heavy resistance/power strength training in middle-aged and older men and women.

The effects of a 6-month resistance training (2 day/week) designed to develop both strength and power on neural activation by electromyographic activity (EMG) of the agonist and antagonist knee extensors, muscle fibre proportion and areas of type I, IIa, and IIb of the vastus lateralis (VL) as well as maximal concentric one repetition maximum (1 RM) strength and maximal and explosive isometric strength of the knee extensors were examined. A total of 10 middle-aged men (M40; 42 +/- 2), 11 middle-aged women (W40; 39 +/- 3), 11 elderly men (M70; 72 +/- 3) and 10 elderly women (W70; 67 +/- 3) served as subjects. Maximal and explosive strength values remained unaltered during a 1-month control period. After the 6-month training maximal isometric and 1RM strength values increased in M40 by 28 +/- 14 and 27 +/- 7% (P < 0.001), in M70 by 27 +/- 17 and 21 +/- 9% (P < 0.001), in W40 by 27 +/- 19 and 35 +/- 14% (P < 0.001) and in W70 by 26 +/- 14 and 31 +/- 14% (P < 0.001), respectively. Explosive strength improved in M40 by 21 +/- 41% (P < 0.05), in M70 by 21 +/- 24% (P < 0.05), in W40 by 32 +/- 45% (NS) and in W70 by 22 +/- 28% (P < 0.05). The iEMGs of the VL and vastus medialis (VM) muscles increased during the training in M40 (P < 0.001 and 0.05), in M70 (P < 0.001 and 0.05), in W40 (P < 0.001 and 0.05) and in W70 (P < 0.001 and 0.05). The antagonist biceps femoris (BF) activity during the isometric knee extension remained unaltered in M40, in W40, and in M70 but decreased in W70 (from 42 +/- 34 to 32 +/- 26%; P < 0.05) during the first 2 months of training. Significant increases occurred during the training in the mean fibre areas of type I in W70 (P < 0.05) and of overall type II along with a specific increase in IIa in both W40 (P < 0.05) and in W70 (P < 0.05), while the changes in the male groups were not statistically significant. The individual percentage values for type II fibres at pretraining correlated with the individual values for 1 RM strength in both W70 (r=0.80; P < 0.05) and M70 (r=0.61; P < 0.05) and also at post-training for maximal isometric torque in W70 (r=0.77, P < 0.05). The findings support the concept of the important role of neural adaptations in strength and power development in middle-aged and older men and women. The muscle fibre distribution (percentage type II fibres) seems to be an important contributor on muscle strength in older people, especially older women. Women of both age groups appear to be hypertrophically responsive to the total body strength training protocol performed two times a week including heavier and lower (for fast movements) loads designed for both maximal strength and power development, while such a programme has limited effects on muscle hypertrophy in men.

Adult↗

PubMed2001

Resistance training combined with bench-step aerobics enhances women's health profile.

PURPOSE: The purpose of this study was to investigate the comprehensive physiological alterations that take place during the combination of bench-step aerobics (BSA) and resistance exercise training. METHODS: Thirty-five healthy, active women were randomly assigned to one of four groups that either a) performed 25 min of BSA only (SA25); b) performed a combination of 25 min of BSA and a multiple-set upper and lower body resistance exercise program (SAR); c) performed 40 min of BSA only (SA40); or d) served as a control group (C), only performing activities of daily living. Direct assessments for body composition, aerobic fitness, muscular strength, endurance, power, and cross-sectional area were performed 1 wk before and after 12 wk of training. RESULTS: All training groups significantly improved peak VO(2) (3.7 to 5.3 mL O(2).kg(-1).min(-1)), with the greatest improvement observed in the SAR group (P = 0.05). Significant reductions in preexercise heart rates (8-9 bpm) and body fat percent (5--6%) were observed in all training groups after training. Significant reductions in resting diastolic blood pressure were observed for the SAR and SA40 groups (6.7 and 5.8 mm Hg, respectively). Muscular strength and endurance only improved significantly in the SAR group (21 and 11% respectively). All groups demonstrated increased lower body power (11--14%), but only the SAR group significantly improved upper body power (32%). Thigh muscle cross-sectional areas measured via magnetic resonance imaging (MRI) increased primarily for the SAR group. CONCLUSION: BSA is an exercise modality effective for improving physical fitness and body composition in healthy women. The addition of resistance exercise appears to enhance the total fitness profile by improving muscular performances, muscle morphology, and cardiovascular fitness greater than from performing BSA alone. Therefore, the inclusion of both modalities to an exercise program is most effective for improving total body fitness and a woman's health profile.

Adult↗

PubMed2001

Low-volume circuit versus high-volume periodized resistance training in women.

PURPOSE: The purpose of this investigation was to determine the long-term training adaptations associated with low-volume circuit-type versus periodized high-volume resistance training programs in women. METHODS: 34 healthy, untrained women were randomly placed into one of the following groups: low-volume, single-set circuit (SSC; N = 12); periodized high-volume multiple-set (MS; N = 12); or nonexercising control (CON) group (N = 10). The SSC group performed one set of 8-12 repetitions to muscular failure 3 d x wk(-1). The MS group performed two to four sets of 3-15 repetitions with periodized volume and intensity 4 d x wk(-1). Muscular strength, power, speed, endurance, anthropometry, and resting hormonal concentrations were determined pretraining (T1), after 12 wk (T2), and after 24 wk of training (T3). RESULTS: 1-RM bench press and leg press, and upper and lower body local muscular endurance increased significantly (P < or = 0.05) at T2 for both groups, but only MS showed a significant increase at T3. Muscular power and speed increased significantly at T2 and T3 only for MS. Increases in testosterone were observed for both groups at T2 but only MS showed a significant increase at T3. Cortisol decreased from T1 to T2 and from T2 to T3 in MS. Insulin-like growth factor-1 increased significantly at T3 for SSC and at T2 and T3 for MS. No changes were observed for growth hormone in any of the training groups. CONCLUSION: Significant improvements in muscular performance may be attained with either a low-volume single-set program or a high-volume, periodized multiple-set program during the first 12 wk of training in untrained women. However, dramatically different training adaptations are associated with specific domains of training program design which contrast in speed of movement, exercise choices and use of variation (periodization) in the intensity and volume of exercise.

Adaptation, Physiological↗

PubMed2001

Effect of resistance training on women's strength/power and occupational performances.

PURPOSE: The effects of resistance training programs on strength, power, and military occupational task performances in women were examined. METHODS: Untrained women aged (mean +/- SD) 23 +/- 4 yr were matched and randomly placed in total- (TP, N = 17 and TH, N = 18) or upper-body resistance training (UP, N = 18 and UH, N = 15), field (FLD, N = 14), or aerobic training groups (AER, N = 11). Two periodized resistance training programs (with supplemental aerobic training) emphasized explosive exercise movements using 3- to 8-RM training loads (TP, UP), whereas the other two emphasized slower exercise movements using 8- to 12-RM loads (TH, UH). The FLD group performed plyometric and partner exercises. Subjects were tested for body composition, strength, power, endurance, maximal and repetitive box lift, 2-mile loaded run, and U.S. Army Physical Fitness Tests before (T0) and after 3 (T3) and 6 months of training (T6). For comparison, untrained men (N = 100) (MEN) were tested once. RESULTS: Specific training programs resulted in significant increases in body mass (TP), 1-RM squat (TP, TH, FLD), bench press (all except AER), high pull (TP), squat jump (TP, TH, FLD), bench throw (all except AER), squat endurance (all except AER), 1-RM box lift (all except aerobic), repetitive box lift (all), push-ups (all except AER), sit-ups (all except AER), and 2-mile run (all). CONCLUSIONS: Strength training improved physical performances of women over 6 months and adaptations in strength, power, and endurance were specific to the subtle differences (e.g., exercise choice and speeds of exercise movement) in the resistance training programs (strength/power vs strength/hypertrophy). Upper- and total-body resistance training resulted in similar improvements in occupational task performances, especially in tasks that involved upper-body musculature. Finally, gender differences in physical performance measures were reduced after resistance training in women, which underscores the importance of such training for physically demanding occupations.

Adolescent↗

PubMed2001

Maximal strength and power, endurance performance, and serum hormones in middle-aged and elderly men.

PURPOSE: To examine maximal strength, power and muscle cross-sectional area, maximal and submaximal cycling endurance characteristics, and serum hormone concentrations of testosterone (T), free testosterone (FT), and cortisol (C) in middle-aged and elderly men. METHODS: Maximal knee extension force (isometric; MIF(KE)), power-load curves during concentric actions with loads ranging from 15% to 70% of 1 RM half-squat (1RM(HS)), muscle cross-sectional area of quadriceps femoris (CSA(QF)), workload, heart rate and lactate accumulation during incremental cycling, and serum hormone concentrations were measured in 26 middle-aged (M42 yr) and 21 elderly men (M65 yr). RESULTS: The 1RM(HS) (14%), MIF(KE) (24%) and CSA(QF) (13%) were lower in M65 than in M42 (P < 0.05-0.01). Power during submaximal actions was lower (P < 0.05-0.001) in M65 than in M42, but the differences disappeared when expressed relative to CSA(QF). Serum FT was in M42 higher (P < 0.05) than in M65. Maximal workload, maximal heart rate and peak blood lactate during cycling in M65 were 31%, 11%, and 20% lower than in M42 (P < 0.01). During submaximal cycling blood lactate rose more rapidly with increasing workload in M65 than in M42 (P < 0.05-0.01), but the differences disappeared when expressed relative to CSA(QF). Significant correlations existed between individual values of serum FT:C ratio, C and T, and those of muscle strength and maximal workload. CONCLUSION: Declines in maximal strength, muscle mass, and endurance performance seem to take place with increasing age, although muscle power and demand for aerobic energy per unit of muscle tissue during submaximal loads remain similar. The balance between anabolic and catabolic hormones in aging people over the years may be associated with age-related decreased strength and declines in maximal cycling workload.

Adult↗

PubMed2001

Testosterone responses after resistance exercise in women: influence of regional fat distribution.

Regional fat distribution (RFD) has been associated with metabolic derangements in populations with obesity. For example, upper body fat patterning is associated with higher levels of free testosterone (FT) and lower levels of sex-hormone binding globulin (SHBG). We sought to determine the extent to which this relationship was true in a healthy (i.e., non-obese) female population and whether RFD influenced androgen responses to resistance exercise. This study examined the effects of RFD on total testosterone (TT), FT, and SHBG responses to an acute resistance exercise test (ARET) among 47 women (22+/-3 years; 165+/-6 cm; 62+/-8 kg; 25+/-5%BF; 23+/-3 BMI). RFD was characterized by 3 separate indices: waist-to-hip ratio (WHR), ratio of upper arm fat to mid-thigh fat assessed with magnetic resonance imaging (MRI ratio), and ratio of subscapular to triceps ratio (SB/TRi ratio). Skinfolds were measured for the triceps, chest, subscapular, mid-axillary, suprailaic, abdomen, and thigh regions. The ARET consisted of 6 sets of 10 RM squats separated by 2-min rest periods. Blood was obtained pre- and post- ARET. TT, FT, and SHBG concentrations were determined by radioimmunoassay. Subjects were divided into tertiles from the indices of RFD, and statistical analyses were performed by an ANOVA with repeated measures (RFD and exercise as main effects). Significant (p < or = .05) increases following the AHRET were observed for TT (approximately 25%), FT (approximately 25%), and SHBG (4%). With multiple regression analysis, anthropometric measures significantly predicted pre- concentrations of FT, post-concentrations of TT, and pre-concentrations of SHBG. The SB/TRi and MRI ratios but not the WHR, were discriminant for hormonal concentrations among the tertiles. In young, healthy women, resistance exercise can induce transient increases in testosterone, and anthropometric markers of adiposity correlate with testosterone concentrations.

Adipose Tissue↗

PubMed2001

Strength training induced adaptations in neuromuscular function of premenopausal women with fibromyalgia: comparison with healthy women.

OBJECTIVE: To investigate the effects of 21 weeks' progressive strength training on neuromuscular function and subjectively perceived symptoms in premenopausal women with fibromyalgia (FM). METHODS: Twenty one women with FM were randomly assigned to experimental (FM(T)) or control (FM(C)) groups. Twelve healthy women served as training controls (H(T)). The FM(T) and H(T) groups carried out progressive strength training twice a week for 21 weeks. The major outcome measures were muscle strength and electromyographic (EMG) recordings. Secondary outcome measures were pain, sleep, fatigue, physical function capacity (Stanford Health Assessment Questionnaire), and mood (short version of Beck's depression index). RESULTS: Female FM(T) subjects increased their maximal and explosive strength and EMG activity to the same extent as the H(T) group. Moreover, the progressive strength training showed immediate benefits on subjectively perceived fatigue, depression, and neck pain of training patients with FM. CONCLUSIONS: The strength training data indicate comparable trainability of the neuromuscular system of women with FM and healthy women. Progressive strength training can safely be used in the treatment of FM to decrease the impact of the syndrome on the neuromuscular system, perceived symptoms, and functional capacity. These results confirm the opinion that FM syndrome has a central rather than a peripheral or muscular basis.

Adult↗

PubMed2001

Effects of strength training on muscle power and serum hormones in middle-aged and older men.

Effects of 16-wk strength training on maximal strength and power performance of the arm and leg muscles and serum concentrations [testosterone (T), free testosterone (FT), and cortisol] were examined in 11 middle-aged (M46; 46 +/- 2 yr) and 11 older men (M64; 64 +/- 2 yr). During the 16-wk training, the relative increases in maximal strength and muscle power output of the arm and leg muscles were significant in both groups (P < 0.05-0.001), with no significant differences between the two groups. The absolute increases were higher (P < 0.01-0.05) in M46 than in M64 mainly during the last 8 wk of training. No significant changes were observed for serum T and FT concentrations. Analysis of covariance showed that, during the 16-wk training period, serum FT concentrations tended to decrease in M64 and increase in M46 (P < 0.05). However, significant correlations between the mean level of individual serum T and FT concentrations and the individual changes in maximal strength were observed in a combined group during the 16-wk training (r = 0.49 and 0.5, respectively; P < 0.05). These data indicate that a prolonged total strength-training program would lead to large gains in maximal strength and power load characteristics of the upper and lower extremity muscles, but the pattern of maximal and power development seemed to differ between the upper and lower extremities in both groups, possibly limited in magnitude because of neuromuscular and/or age-related endocrine impairments.

Aged↗

PubMed2001

Selective muscle hypertrophy, changes in EMG and force, and serum hormones during strength training in older women.

Effects of strength training (ST) for 21 wk were examined in 10 older women (64 +/- 3 yr). Electromyogram, maximal isometric force, one-repetition maximum strength, and rate of force development of the leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF) and of vastus lateralis (VL), medialis (VM), intermedius (VI) and rectus femoris (RF) throughout the lengths of 3/12--12/15 (Lf) of the femur, muscle fiber proportion and areas of types I, IIa, and IIb of the VL were evaluated. Serum hormone concentrations of testosterone, growth hormone (GH), cortisol, and IGF-I were analyzed for the resting, preexercise, and postexercise conditions. After the 21-wk ST, maximal force increased by 37% (P < 0.001) and 1-RM by 29% (P < 0.001), accompanied by an increase (P < 0.01) in rate of force development. The integrated electromyograms of the vastus muscles increased (P < 0.05). The CSA of the total QF increased (P < 0.05) throughout the length of the femur by 5--9%. The increases were significant (P < 0.05) at 7/15--12/15 Lf for VL and at 3/15--8/15 Lf for VM, at 5/15--9/15 for VI and at 9/15 (P < 0.05) for RF. The fiber areas of type I (P < 0.05), IIa (P < 0.001), and IIb (P < 0.001) increased by 22--36%. No changes occurred during ST in serum basal concentrations of the hormones examined, but the level of testosterone correlated with the changes in the CSA of the QF (r = 0.64, P < 0.05). An acute increase of GH (P < 0.05), remaining elevated up to 30 min (P < 0.05) postloading, was observed only at posttraining. Both neural adaptations and the capacity of skeletal muscle to undergo training-induced hypertrophy even in older women explain the strength gains. The increases in the CSA of the QF occurred throughout its length but differed selectively between the individual muscles. The serum concentrations of hormones remained unaltered, but a low level of testosterone may be a limiting factor in training-induced muscle hypertrophy. The magnitude and time duration of the acute GH response may be important physiological indicators of anabolic adaptations during strength training even in older women.

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