Enhanced endurance in trained cyclists during moderate intensity exercise following 2 weeks adaptation to a high fat diet

These studies investigated the effects of 2 weeks of either a high-fat (HIGH-FAT: 70% fat, 7% CHO) or a high-carbohydrate (HIGH-CHO: 74% CHO, 12% fat) diet on exercise performance in trained cyclists (n = 5) during consecutive periods of cycle exercise including a Wingate test of muscle power, cycle exercise to exhaustion at 85% of peak power output [90% maximal oxygen uptake ( O_2max), high-intensity exercise (HIE)] and 50% of peak power output [60% O_2max, moderate intensity exercise (MIE)]. Exercise time to exhaustion during HIE was not significantly different between trials: nor were the rates of muscle glycogen utilization during HIE different between trials, although starting muscle glycogen content was lower [68.1 (SEM 3.9) vs 120.6 (SEM 3.8) mmol · kg ^–1 wet mass, P < 0.01] after the HIGH-FAT diet. Despite a lower muscle glycogen content at the onset of MIE [32 (SEM 7) vs 73 (SEM 6) mmol · kg ^–1 wet mass, HIGH-FAT vs HIGH-CHO, P < 0.01], exercise time to exhaustion during subsequent MIE was significantly longer after the HIGH-FAT diet [79.7 (SEM 7.6) vs 42.5 (SEM 6.8) min, HIGH-FAT vs HIGH-CHO, P<0.01]. Enhanced endurance during MIE after the HIGH-FAT diet was associated with a lower respiratory exchange ratio [0.87 (SEM 0.03) vs 0.92 (SEM 0.02), P<0.05], and a decreased rate of carbohydrate oxidation [1.41 (SEM 0.70) vs 2.23 (SEM 0.40) g CHO · min^–1, P<0.05]. These results would suggest that 2 weeks of adaptation to a high-fat diet would result in an enhanced resistance to fatigue and a significant sparing of endogenous carbohydrate during low to moderate intensity exercise in a relatively glycogen-depleted state and unimpaired performance during high intensity exercise.     

Neuromuscular and hormonal adaptations in athletes to strength training in two years

Neuromuscular and hormonal adaptations to prolonged strength training were investigated in nine elite weight lifters. The average increases occurred over the 2-yr follow-up period in the maximal neural activation (integrated electromyogram, IEMG; 4.2%, P = NS), maximal isometric leg-extension force (4.9%, P = NS), averaged concentric power index (4.1%, P = NS), total weight-lifting result (2.8%, P less than 0.05), and total mean fiber area (5.9%, P = NS) of the vastus lateralis muscle, respectively. The training period resulted in increases in the concentrations of serum testosterone from 19.8 +/- 5.3 to 25.1 +/- 5.2 nmol/l (P less than 0.05), luteinizing hormone (LH) from 8.6 +/- 0.8 to 9.1 +/- 0.8 U/l (P less than 0.05), follicle-stimulating hormone (FSH) from 4.2 +/- 2.0 to 5.3 +/- 2.3 U/l (P less than 0.01), and testosterone-to-serum sex hormone-binding globulin (SHBG) ratio (P less than 0.05). The annual mean value of the second follow-up year for the serum testosterone-to-SHBG ratio correlated significantly (r = 0.84, P less than 0.01) with the individual changes during the 2nd yr in the averaged concentric power. The present results suggest that prolonged intensive strength training in elite athletes may influence the pituitary and possibly hypothalamic levels, leading to increased serum levels of testosterone. This may create more optimal conditions to utilize more intensive training leading to increased strength development.     

Neuromuscular training improves performance and lower-extremity biomechanics in female athletes

The purpose of this study was to examine the effects of a comprehensive neuromuscular training program on measures of performance and lower-extremity movement biomechanics in female athletes. The hypothesis was that significant improvements in measures of performance would be demonstrated concomitant with improved biomechanical measures related to anterior cruciate ligament injury risk. Forty-one female basketball, soccer, and volleyball players (age, 15.3 +/- 0.9 years; weight, 64.8 +/- 9.96 kg; height, 171.2 +/- 7.21 cm) underwent 6 weeks of training that included 4 main components (plyometric and movement, core strengthening and balance, resistance training, and speed training). Twelve age-, height-, and weight-matched controls underwent the same testing protocol twice 6 weeks apart. Trained athletes demonstrated increased predicted 1 repetition maximum squat (92%) and bench press (20%). Right and left single-leg hop distance increased 10.39 cm and 8.53 cm, respectively, and vertical jump also increased from 39.9 +/- 0.9 cm to 43.2 +/- 1.1 cm with training. Speed in a 9.1-m sprint improved from 1.80 +/- 0.02 seconds to 1.73 +/- 0.01 seconds. Pre- and posttest 3-dimensional motion analysis demonstrated increased knee flexion-extension range of motion during the landing phase of a vertical jump (right, 71.9 +/- 1.4 degrees to 76.9 +/- 1.4 degrees ; left, 71.3 +/- 1.5 degrees to 77.3 +/- 1.4 degrees ). Training decreased knee valgus (28%) and varus (38%) torques. Control subjects did not demonstrate significant alterations during the 6-week interval. The results of this study support the hypothesis that the combination of multiple-injury prevention-training components into a comprehensive program improves measures of performance and movement biomechanics.     

The effectiveness of resisted jump training on the VertiMax in high school athletes

Resisted jumping devices and resisted plyometric training have become more common in recent years. The effectiveness of such training has yet to be determined among high school athletes. Sixty-four high school athletes (50 boys and 14 girls) from a variety of sports were divided into 2 groups and participated in a training intervention that differed only by the use of the VertiMax jump trainer in 1 group. Lower-body power was tested before and after the intervention and compared statistically for differences between the groups. Athletes from both groups followed a periodized training program with resistance exercises performed 2 or 3 days per week, and sprint and plyometric training (i.e., training control group) or sprint, plyometric, and VertiMax training (i.e., VertiMax group) 1 or 2 days per week, for 12 total weeks. In addition to the traditional compound lower-body lifts and equated sprint work, the VertiMax group performed supplementary exercises on the VertiMax training apparatus. The average improvement in power observed in the training control group was 49.50 +/- 97.83 W, and the increase in power in the VertiMax group was 217.14 +/- 99.21 W. The differences in power after the test and improvements in power with training were found to differ between the groups (P < 0.05) and favored the VertiMax training group. Combined with previous research with college athletes, these data show the added effectiveness of resisted jump training on the VertiMax among athletes for the development of lower-body power.     

Effect of twelve weeks of medicine ball training on high school baseball players

This study examined the effect of 12 weeks of medicine ball training on high school baseball players. Forty-nine baseball players (age 15.4 +/- 1.2 years) were randomly assigned using a stratified sampling technique to 1 of 2 groups. Group 1 (n = 24) and group 2 (n = 25) performed the same full-body resistance exercises according to a stepwise periodized model and took 100 bat swings a day, 3 days per week, with their normal game bat for 12 weeks. Group 2 performed additional rotational and full-body medicine ball exercises 3 days per week for 12 weeks. Pre- and post-testing consisted of a 3 repetition maximum (RM) dominant and nondominant torso rotational strength and sequential hip-torso-arm rotational strength (medicine ball hitter's throw). A 3RM parallel squat and bench press were measured at 0 and after 4, 8, and 12 weeks of training. Although both groups made statistically significant increases (p < or = 0.05) in dominant (10.5 vs. 17.1%) and nondominant (10.2 vs. 18.3%) torso rotational strength and the medicine ball hitter's throw (3.0 vs. 10.6%), group 2 showed significantly greater increases in all 3 variables than group 1. Furthermore, both groups made significant increases in predicted 1RM parallel squat and bench press after 4, 8, and 12 weeks of training; however, there were no differences between groups. These data indicate that performing a 12-week medicine ball training program in addition to a stepwise periodized resistance training program with bat swings provided greater sport-specific training improvements in torso rotational and sequential hip-torso-arm rotational strength for high school baseball players.     

Predicting strength in high school women athletes

The purpose of this study was to investigate the hypothesis that a repetitions-to-maximum test is a predicator of a 1 repetition maximum (1RM) performance for evaluating upper and lower body strength in women high school athletes. Fifty-seven high school athletes ages 14-18 participated in this study. All of the participants completed a 1RM bench (1RMBP) and leg press (1RMLP) test, as well as leg press repetitions-to-fatigue (91 kg; LPRTF91) and bench press repetitions-to-fatigue (27 kg; BPRTF27) tests. A Pearson product correlation and regression analysis was used to determine relationships between 1RM strength and the repetitions-to-fatigue for upper and lower body strength. On the basis of the data analysis, it was concluded that BPRTF27 had a high correlation with 1RMBP strength (r = 0.802) and LPRTF91 had a correlation with 1RMLP strength (r = 0.793), indicating that these test measures were viable alternatives to 1RM testing for strength assessment. A regression analysis further confirmed that BPRTF27 was a significant variables in developing the model 1RMBP = 28.88 + (0.68)BPRTF27 for predicting upper body strength (p < 0.001). Similar results occurred 1RMLP = 106.3 + (2.4)LPRTF91 in developing the lower body model (p < 0.001). From data analysis, it was concluded that repetitions-to-fatigue testing can be used to evaluate upper and lower body strength in women high school athletes.     

Effect of 12 weeks of wrist and forearm training on high school baseball players

This study examined the effect of 12 weeks of wrist and forearm training on male high school baseball players (mean age = 15.3 +/- 1.1 years). Participants (N = 43) were tested for 10 repetition maximum (RM) wrist barbell flexion, wrist barbell extension, dominant (D) and nondominant (ND) hand-forearm supination, D and ND forearm pronation, D and ND wrist radial deviation, D and ND wrist ulnar deviation, D and ND grip strength, and a 3RM parallel squat (PS) and bench press (BP). Group 1 (n = 23) and group 2 (n = 20), randomly assigned by a stratified sampling technique, performed the same resistance exercises while training 3 days a week for 12 weeks according to a stepwise periodized model. Group 2 also performed wrist and forearm exercises 3 days a week for 12 weeks to determine if additional wrist and forearm training provided further wrist and forearm strength improvements. All wrist and forearm strength variables were measured before and after 12 weeks of training. The 3RM PS and BP were measured at 0 and after 4, 8, and 12 weeks of training. Both groups significantly increased wrist and forearm strength (kg +/- SD) except 10RM D and ND forearm supination for group 1 (p < 0.05). Group 2 showed statistically greater improvements (p < 0.05) in all wrist and forearm strength variables than did group 1 except for D and ND grip strength. Predicted 1RM (kg +/- SD) PS and BP increased significantly (p < 0.05) after weeks 4, 8, and 12 for both groups. These data indicate that a 12-week stepwise periodized training program can significantly increase wrist, forearm, PS, and BP strength for both groups. Additionally, group 2 had further wrist and forearm strength gains.     

Neuromuscular and hormonal responses in elite athletes to two successive strength training sessions in one day

Acute neuromuscular and endocrine adaptations to weight-lifting were investigated during two successive high intensity training sessions in the same day. Both the morning (I) (from 9.00 to 11.00 hours) and the afternoon (II) (from 15.00 hours to 17.00 hours) training sessions resulted in decreases in maximal isometric strength (p less than 0.01 and less than 0.05), shifts (worsening) in the force-time curve in the absolute scale (p less than 0.05 and ns.) and in decreases in the maximal integrated EMG (p less than 0.01 and less than 0.05) of the selected leg extensor muscles. Increases in serum total (p less than 0.05) and free testosterone (p less than 0.01) and in cortisol (p less than 0.01) concentrations were found during training session II. These were followed by decreases (p less than 0.001 and p less than 0.01 and ns.) in the levels of these hormones one hour after the termination of the session. The responses during the morning training session were different with regard to the decreases in serum total testosterone (p less than 0.05), free testosterone (ns.) and cortisol (p less than 0.05). Only slight changes were observed in the levels of luteinizing hormone and sex hormone-binding globulin during the training sessions. Increases (p less than 0.01) took place in somatotropin during both training sessions. The present findings suggest that high intensity strengthening exercises may result in acute adaptive responses in both the neuromuscular and endocrine systems. The diurnal variations may, however, partly mask the exercise-induced acute endocrinological adaptations in the morning.(ABSTRACT TRUNCATED AT 250 WORDS)     

Limb skeletal muscle adaptation in athletes after training at altitude

Morphological and biochemical characteristics of biopsies obtained from gastrocnemius (GAS) and triceps brachii muscle (TRI), as well as maximal O2 uptake (VO2 max) and O2 deficit, were determined in 10 well-trained cross-country skiers before and after a 2-wk stay (2,100 m above sea level) and training (2,700 m above sea level) at altitude. On return to sea level, VO2 max was the same as the prealtitude value, whereas an increase in O2 deficit (29%) and in short-term running performance (17%) was observed (P less than 0.05). GAS showed maintained capillary supply but a 10% decrease in mitochondrial enzyme activities (P less than 0.05), whereas an increase in capillary supply (P less than 0.05) but unchanged mitochondrial enzyme activities were observed in TRI. Buffer capacity was increased by 6% in both GAS and TRI (P less than 0.05). A positive correlation was found between the relative increase in buffer capacity of GAS and short-term running time (P less than 0.05). Thus the present study indicates no effect of 2 wk of altitude training on VO2 max but provides evidence to suggest an improvement in short-term exercise performance, which may be the result of an increase in muscle buffer capacity.     

Changes in fibrinolysis components during short-term adaptation to high altitude]

In studying hemocoagulation in dogs under conditions of Frunze (760 m above the sea level) and Tuya-Ashu (3200 m above the sea level) it was shown that in the "emergency" phase of adaptation (the first three days) there was seen activation of fibrinolysin and profibrinolysin with depression of antifibrinolysins and inhibitors of profibrinolysin activators. The concentration of plasma fibrinogen at that period decreased by 100 mg%, which could promote an increase in the vascular permeability and improvement of oxygen approach to the tissues. Later, along with elevation of fibrinolysin and profibrinolysin activators there was a marked increase in the level of fibrinolysis inhibitors. Correlation of all the fibrinolysis components was established at a new level.     

Neuromuscular adaptations and serum hormones in women during short-term intensive strength training

The effects were investigated in ten women of intensive heavy resistance strength training lasting for 3 weeks on electromyographic (EMG) activity, muscle cross-sectional area (CSA) and voluntary force production characteristics of leg extensor muscles. Blood samples for the determinations of serum hormones were taken from five of the subjects. Significant increases occurred in the higher force portions of the isometric force-time curve with an increase of 9.7 (SD 8.4)% (P less than 0.01) in maximal peak force. An increase of 15.8 (SD 20.9)% (P less than 0.05) took place also in the maximal neural activation (integrated EMG) of the trained muscles, while an enlargement of 4.6 (SD 7.4)% (P less than 0.05) occurred in the CSA of the quadriceps femoris muscle. Maximal force per muscle CSA increased significantly (P less than 0.05). No statistically significant changes were observed during the training in the mean concentrations of serum testosterone, free testosterone, cortisol and sex hormone binding globulin (SHBG). The individual concentrations of serum testosterone:SHBG ratio correlated with the individual changes obtained during the training in the muscle CSA (r = 0.99; P less than 0.01). The present findings in women indicated that the increases in maximal strength during short-term but intensive strength training were primarily due to the increased voluntary activation of the trained muscles, while muscle hypertrophy remained limited in magnitude. Large interindividual differences in women in serum testosterone concentrations could indicate corresponding differences in muscle hypertrophy and strength development even during a short-term but intensive strength training period.     

Effects of 6 weeks of periodized squat training with or without whole-body vibration on short-term adaptations in jump performance within recreationally resistance trained men

The purpose of this study was to examine the effects of a 6-week, periodized squat training program, with or without whole-body low-frequency vibration (WBLFV), on jump performance. Males ranged in age from 20 to 30 years and were randomized into groups that did squat training with (SQTV, n = 13) or without (SQT, n = 11) vibration, or a control group (CG, n = 6). Measures of jump height (cm), peak power (Pmax), Pmax per kilogram of body mass (Pmax/kg), and mean power were recorded during 30-cm depth jumps and 20-kg squat jumps at weeks 1 (pretraining), 3 (midtraining), and 7 (posttraining). No significant group differences were seen for 30-cm depth jump height between weeks 1 and 7 (p > 0.05). Trial three (W7) measures were greater than those for trial two (W3) and trial one (W1) (p < 0.05). Significant group differences were seen for 20-kg squat jump height, with SQTV > SQT between weeks 1 and 7 (p < 0.05). Significant trial differences were seen, with W7 > W3 > W1 (p < 0.05) as well as for 30-cm depth jump Pmax percent change (W7 > W3 and W1 p < 0.05)). A significant trial effect was seen for 20-kg squat jump Pmax (W7 > W1, p < 0.05) and 20-kg squat jump Pmax/kg percent change (W7 > W3 > W1, p < 0.05). The addition of vibration to SQTV seemed to facilitate Pmax and mean power adaptation for depth jumps and Pmax for squat jumps, although not significantly (p > 0.05). Stretch reflex potentiation and increased motor unit synchronization and firing rates may account for the trends seen. Baseline squat strength, resistance training experience, and amplitude, frequency, and duration of application of WBLFV seem to be important factors that need to be controlled for.     

Effects of six weeks of beta-hydroxy-beta-methylbutyrate (HMB) and HMB/creatine supplementation on strength, power, and anthropometry of highly trained athletes

This study investigated the effects of 6 weeks of dietary supplementation of beta-hydroxy-beta-methylbutyrate (HMB) and HMB combined with creatine monohydrate (HMBCr) on the muscular strength and endurance, leg power, and anthropometry of elite male rugby league players. The subjects were divided into a control group (n = 8), a HMB group (n = 11; 3 g.d(-1)) or a HMBCr group (n = 11; 12 g.d(-1) with 3 g HMB, 3 g Cr, 6 g carbohydrates). Three repetition maximum lifts on bench press, deadlifts, prone row, and shoulder press, maximum chin-up repetitions, 10-second maximal cycle test, body mass, girths, and sum of skinfolds were assessed pre- and postsupplementation. Statistical analysis revealed no effect of HMB or HMBCr on any parameter compared with presupplementation measures or the control group. HMB and HMBCr were concluded to have no ergogenic effect on muscular strength and endurance, leg power, or anthropometry when taken orally by highly trained male athletes over 6 weeks.     

Proteomic adaptation to chronic high intensity swimming training in the rat heart

Cardiac hypertrophy induced by exercise is associated with less cardiac fibrosis and better systolic and diastolic function, suggesting that the adaptive mechanisms may exist in exercise-induced hypertrophy. To identify molecular mechanisms by which exercise training stimulates this favorable phenotype, a proteomic approach was employed to detect rat cardiac proteins that were differentially expressed or modified after exercise training. Sixteen male Sprague–Dawley rats were divided into trained (T) and control(C). T rats underwent eight weeks of swimming training seven days/week, using a high intensity protocol. Hearts were used to generate 2-D electrophoretic proteome maps. Training significantly altered 23 protein spot intensities (P < 0.05), including proteins associated with the mitochondria oxidative metabolism, such as prohibitin, malate dehydrogenase, short-chain acyl-CoA dehydrogenase, triosephosphate isomerase, electron transfer flavoprotein subunit beta, ndufa10 protein, ATP synthase subunit alpha and isocitrate dehydrogenase [NAD] subunit. Additionally, Prohibitin was increased in the exercise-induced hearts. Cytoskeletal, signal pathway, stress and oxidative proteins also increased within T groups. These results strongly support the notion that the observed changes in the expression of energy metabolism proteins resulted in a potential increase in the capacity to synthesise ATP, probably via mitochondrial oxidative metabolism. The observed changes in the expression of these metabolic and structural proteins induced by training may beneficially influence heart metabolism, stress response and signalling paths, and therefore improve the overall cardiac function.     

Interaction of contractile activity and training history on mRNA abundance in skeletal muscle from trained athletes

Skeletal muscle displays enormous plasticity to respond to contractile activity with muscle from strength- (ST) and endurance-trained (ET) athletes representing diverse states of the adaptation continuum. Training adaptation can be viewed as the accumulation of specific proteins. Hence, the altered gene expression that allows for changes in protein concentration is of major importance for any training adaptation. Accordingly, the aim of the present study was to quantify acute subcellular responses in muscle to habitual and unfamiliar exercise. After 24-h diet/exercise control, 13 male subjects (7 ST and 6 ET) performed a random order of either resistance (8 x 5 maximal leg extensions) or endurance exercise (1 h of cycling at 70% peak O2 uptake). Muscle biopsies were taken from vastus lateralis at rest and 3 h after exercise. Gene expression was analyzed using real-time PCR with changes normalized relative to preexercise values. After cycling exercise, peroxisome proliferator-activated receptor-gamma coactivator-1alpha (ET approximately 8.5-fold, ST approximately 10-fold, P < 0.001), pyruvate dehydrogenase kinase-4 (PDK-4; ET approximately 26-fold, ST approximately 39-fold), vascular endothelial growth factor (VEGF; ET approximately 4.5-fold, ST approximately 4-fold), and muscle atrophy F-box protein (MAFbx) (ET approximately 2-fold, ST approximately 0.4-fold) mRNA increased in both groups, whereas MyoD (approximately 3-fold), myogenin (approximately 0.9-fold), and myostatin (approximately 2-fold) mRNA increased in ET but not in ST (P < 0.05). After resistance exercise PDK-4 (approximately 7-fold, P < 0.01) and MyoD (approximately 0.7-fold) increased, whereas MAFbx (approximately 0.7-fold) and myostatin (approximately 0.6-fold) decreased in ET but not in ST. We conclude that prior training history can modify the acute gene responses in skeletal muscle to subsequent exercise.     

The effects of combined ballistic and heavy resistance training on maximal lower- and upper-body strength in recreationally trained men

The purpose of the present study was to investigate the additive effects of ballistic training to a traditional heavy resistance training program on upper- and lower-body maximal strength. Seventeen resistance-trained men were randomly assigned to 1 of 2 groups: (i) a combined ballistic and heavy resistance training group (COM; age = 21.4 +/- 1.7 years, body mass = 82.7 +/- 15.1 kg) or (ii) a heavy resistance training group (HR; age = 20.1 +/- 1.2 years, body mass = 81.0 +/- 9.2 kg) and subsequently participated in an 8-week periodized training program. Training was performed 3 days per week, that is, 6-8 exercises per workout (6-8 traditional exercises for HR; 4-6 traditional + 2 ballistic exercises in COM) for 3-8 repetitions. A significant increase in 1-repetition maximum (1RM) squat was shown in both groups (COM = 15.2%; HR = 17.3%) with no difference observed between groups. However, 1RM bench press increased to a significantly greater extent (P = 0.04) in COM than HR (11.6% vs. 7.1%, respectively). For peak power attained during the jump squat, an interaction (P = 0.02) was observed where the 5.4% increase in COM and -3.2% reduction in HR were statistically significant. Nonsignificant increases were observed in peak plyometric push-up power in COM (8.5%) and HR (3.4%). Lean body mass increased significantly in both groups, with no between-group differences observed. The results of this study support the inclusion of ballistic exercises into a heavy resistance training program for increasing 1RM bench press and enhancing lower-body power.     

Optimum onset period for training based on maximum peak velocity of height by wavelet interpolation method in Japanese high school athletes

The Wavelet Interpolation Method (WIM) was applied to the longitudinal records of individuals' heights and weights from 6 to 17 years of age (1983 to 1994) in an athlete group (male: 45, female: 50) and a control group (male: 85, female: 85). The criterion of maturity was derived from age at Maximum Peak Velocity (MPV) of height in the control group. Ages at MPV of height and weight were compared between the athletes and control subjects. The WIM was also applied to mean heights from 6.5 to 17.5 years of all the subjects classified by maturation rate in order to derive a model of growth velocity types.Among the athletes, the males were early-maturing and the females tended to be late-maturing. The difference between the ages at MPV of height and weight in males and females was less in the athletes group than in the control group. For the growth velocity model, in the athlete group, three types could be confirmed among the males, and five among the females. By making use of the type models, it was possible to clarify the spans of adolescence as classified by maturation rates, and it was concluded that the period following the age at MPV seems appropriate for the introduction of regular athletic training for each level of maturity.