The purpose of this investigation was to determine the effects of a concentric vs. eccentric resistance training program on single muscle fiber myosin heavy chain (MHC) adaptations in humans. Fifteen sedentary, healthy males were divided into three groups: concentric training (CTG) (n = 6, 24.2 +/- 1.7 y, 181 2 cm, 82.5 +/- 4.6 kg), eccentric training (ETG) (n=6, 23.7 +/- 1.6 y, 178 +/- 3 cm, 90.4 +/- 6.1 kg), and control (CTL) (n = 3, 23.7 +/- 1.5 y, 181 +/- 2 cm, 97 +/- 13.2 kg). The subjects performed 4 sets of 8 unilateral repetitions starting at 80% of concentric 1-RM, 3 days/ week for a total of 4 weeks. Subjects were tested pre- and post-training for concentric 1-RM. Muscle biopsies were obtained from the vastus lateralis pre- and post-training for determination of single fiber MHC isoform distribution using SDS-PAGE/silver staining (100 fibers analyzed /subject pre- and post-training). Fibers expressing more than one MHC isoform (i.e., hybrid fibers) were analyzed for relative MHC isoform proportions via densitometry. The training program resulted in a19% 1-RM strength gain for CTG (p < 0.05) with no change in ETG or CTL. MHC-IIx fibers decreased by 7% in CTG (p < 0.05) and ETG had an II % increase in total hybrids (MHC-I/IIa + MHC-IIa/IIx) (p < 0.05). No other differences were noted in MHC distribution among the three groups. Densitometry analysis of hybrid fibers showed no change in relative MHC isoform proportions pre- to post-training for any group. These data suggest that the MHC distribution did not change dramatically as a result of 4 weeks of concentric vs. eccentric resistance training despite the increase in whole muscle strength from concentric muscle actions.

PURPOSE:The intent of this investigation was to examine the effects of a daily oral provision consisting of amino acids (L-lysine, L-leucine, L-valine, L-phenylalanine, L-threonine, L-histidine, L-isoleucine, and L-methionine) in combination with carbohydrates (dextrose, sucrose, and fructose) on whole muscle strength and size characteristics during a 12-wk progressive knee extensor resistance training (PRT) program in older men (>65 yr).METHODS:Seventeen older men were randomly assigned to either the experimental (EX) or control (CN) groups. The EX (N = 8) and CN (N = 9) groups had the following characteristics-EX: 70.8 +/- 1.5 yr, 91.0 +/- 4.9 kg, and 177.0 +/- 3.9 cm; CN: 72.1 +/- 1.9 yr, 75.4 +/- 4.7 kg, and 176.1 +/- 3.0. Pre and post PRT maximal unilateral isometric torque (N.m), isokinetic torque (1.05, 1.57, 2.09, 3.14, 4.19, and 5.24 rad.s-1), work capacity (30 consecutive reps at 3.14 rad.s-1) torque, one repetition maximum (1RM) bilateral isotonic strength, and whole muscle cross-sectional area (CSA) of the mid-thigh were performed by computed tomography on each subject.RESULTS:All variables showed an improvement with training (P < 0.05); however, there were no differences between the groups. Both groups increased in isometric strength by 21%, and isokinetic torque by 24% to 11% with the varying velocities (1.05-5.24 rad.s-1). Whole muscle 1RM strength and thigh CSA increased 50% and 6.5%, respectively. Additionally, voluntary torque/CSA increased 12% in both the EX and CN groups (P < 0.05).CONCLUSIONS:In conclusion, these data suggest that whole muscle strength and size are not enhanced with a postexercise daily provision of an oral amino-acid complex during 12 wk of PRT in older men.

The purpose of this investigation was to betermine the effects of ribose supplementation on adenine nucleotide levels (TAN) in human skeletal muscle following high-intensity cycle exercise. An 11-day supplementation period of either ribose (20 g · d−1) or placebo (glucose 20 g · d−1) was employed using 16 healthy collage-aged male subjects (24 yrs, 77kg, 179 cm). After 72 hours of supplementation, subjects performed 5 days of high-intensity exercise, 2 times per day, for a total of 10 sessions. Each exercise session was 15 minutes and consisted of 15 × 10 second sprints at 7% body weight. A 65 hour recovery (with supplementation) period was completed following the 5-d exercise period. Muscle biopsies were performed at 4 different time points during the supplementation/exercise period and analyzed for TAN. Following the exercise period, the TAN of the ribose group decreased (p < 0.05) 38% (7939 ± 271 to 4926 ± 308 nmol·g−1). However, ribose supplementation partially attenuated the decrease in TAN (p < 0.05). Although both groups displayed a similar pattern of recovery in TAN 65 hours following the 5-d exercise period, the ribose group returned to pre-exercise levels, while the placebo group remained 23% below pre-exercise levels (p < 0.05). These data indicate that ribose supplementation partially attenuates the decrease in TAN following 5 days of high-intensity cycle exercise. Thus, ribose may be benificial in short-term replenishment of TAN immediately following a high-intensity exercise bout. Supported, in part, by a grant from Bioenergy, Inc.

The purpose of this investigation was to determine the effects of a 12-week progressive resistance-training program (PRT) on single myofiber calcium sensitivity in six older women (73 ± 2 yr.). Muscle biopsies of the vastus lateralis were obtained pre-and-post PRT. Single muscle fibers were dissected and mounted between a lever arm and force transducer in an experimental chamber. The experimental sequence for each fiber was the determination of maximal isometric tension (Po) at pCa 4.5 (pCa = −log[Ca2+]), and then subsequent submaximal activations of the fiber at nine Ca2+ concentrations (pCa 6.8 to 4.7). MHC I and IIa fiber diameter increased 16% (p < 0.05) and 2% pre-to-post PRT, respectively. Peak isometric tension in MHC I and IIa fibers increased 34% (p < 0.05) and 18% as a result of the training. The mean MHC I Ca2+ activation threshold increased from 6.83 ± 0.02 to 6.91 ± 0.01 (p < 0.05) as did the mean half-maximal activation 5.51 ± 0.02 to 5.71 ± 0.03 (p < 0.05) with PRT. The slope of the Hill plot above (n1) half-maximal activation for MHC I did not change significantly with the PRT (1.80 ± 0.04 to 1.86 ± 0.08). However, the slope of the Hill plot below (n2) half-maximal activation for MHC I demonstrated an increase (p < 0.05) with training (1.70 ± 0.11 to 2.43 ± 0.09). There were no differences with MHC IIa fibers with PRT for any of the Ca2+ variables measured. In conclusion, the results of this investigation indicate that myofibril ca2+ sensitivity and activation properties are altered in MHC I, but not MHC IIa fibers with PRT in older women. The alterations in the MHC I Ca2+ properties appear to have a significant effect on the mechanisms involved with skeletal muscle adaptability in older women following PRT. Supported by NIH AG154876

The purpose of this investigation was to examine the effects of 12 wk of progressive resistance training (PRT) on single muscle fiber myosin heavy chain (MHC; I, I/IIa, I/IIa/IIx, IIa, IIa/IIx, IIx) isoform proportions in young individuals. Young, untrained men (YM; n = 6) and women (YW; n = 6) (age = 22 +/- 1 and 25 +/- 2 yr for YW and YM, respectively) received pre- and post-PRT muscle biopsies from the right vastus lateralis for single muscle fiber MHC distribution by electrophoretic analysis (192 +/- 5 pre- and 183 +/- 6 post-fibers/subject analyzed; 4,495 fibers total). Data are presented as percentages of the total fibers analyzed per subject. The PRT protocol elicited an increase in the pure MHC IIa (Delta = + 24 and + 27; YW and YM, respectively; P < 0.05) with no change in the pure MHC I distribution. The hybrid MHC distributions decreased I/IIa/IIx (Delta = -2; YM and YW; P < 0.05), IIa/IIx (Delta = -13 and -19 for YM and YW, respectively; P < 0.05), and total hybrid fiber proportion (I/IIa + I/IIa/IIx + IIa/IIx) decreased (Delta = -19 and -30 for YM and YW, respectively; P < 0.05) with the training, as did the MHC IIx distribution (Delta = -2; YW only; P < 0.05). Alterations in the predominance of MHC isoforms within hybrid fibers (decrease in MHC I-dominant I/IIa and nondominant MHC IIa/IIx, increase in MHC IIa-dominant IIa/IIx; P < 0.05) appeared to contribute to the increase in the MHC IIa proportion. Electrophoresis of muscle cross sections revealed an approximately 7% increase (P < 0.05) in MHC IIa proportion in both groups, whereas the MHC IIx decrease by 7.5 and 11.6% post-PRT in YW and YM, respectively. MHC I proportions increase in YM by 4.8% (P < 0.05) post-PRT. These findings further support previous resistance training data in young adults with respect to the increase in the MHC IIa proportions but demonstrate that a majority of the change can be attributed to the decrease in single-fiber hybrid proportions.

The purpose of this investigation was to determine the effects of ribose supplementation on power output and fatigue during repeated high-intensity cycle sprints. Sixteen healthy college-aged males (24 ± 1 yrs, 77 ± 3 kg, 179 ± 1 cm) completed an 11-day supplementation period of either ribose (20 g·d−1; n = 8) or placebo (glucose 20 g·d−1; n = 8). After 72 hours of supplementation, subjects performed 5 days of high-intensity exercise 2 times per day for a total of 10 sessions. Each exercise session consisted of 15x10 second sprints at 7% body weight. Exercise was performed on a Monark cycle ergometer (Varberg, Sweden) that was interfaced with a personal computer which allowed for determination of mean and peak power output and fatigue index (Sports Medicine Industries, Inc., St. Cloud, MN). The ribose group had a larger change in mean power (4.2% vs 0.6%) than the placebo group over the 5-day training period. Furthermore, the ribose group had a greater peak power output (p < 0.05, time), at last sprint session (11.4 watts·kg−1) compared to the first sprint session (10.4 watts·kg−1) while no differences were noted in the placebo group (pre = 10.7; post = 11.5 watts·kg−1). There were no group × time interactions for mean power, peak power, and fatigue index. These data suggest that ribose supplementation may provide an ergogenic benefit over-time with high-intensity cycle exercise training. Supported, in part, by Bioenergy, Inc.

This investigation examined alterations in neuromuscular drive for dynamic and static muscle contractions, muscle strength, and cross-sectional area (CSA) with a 12-week progressive resistance-training program (PRT). Nine healthy men (70.0 ± 1.7 years) were evaluated for maximal and submaximal neuromuscular drive (integrated electromyography [IEMG]), whole-muscle strength, isokinetic power, and thigh CSA. The results demonstrated no significant differences pre- to post-PRT in the submaximal IEMG signals ( p > .05). IEMG increased ( p < .05) for the maximal static contraction (29% ± 12%) and isokinetic velocities concentrically and eccentrically. There was an increase ( p < .05) in maximal static strength (27% ± 5%), isokinetic concentric and eccentric strength, muscle power, IRM (47% ± 6%), and CSA (6% ± 1%; p < .05). The results reveal significant neuromuscular-drive alterations in concentric and eccentric dynamic contractions with PRT in older men and indicate that their neuromuscular drive contributes significantly to improving their concentric and eccentric skeletal-muscle strength.

This investigation examined the effects of 4 weeks of non-dominant arm unloading on the functional and structural characteristics of the triceps brachii muscle of six normo-active college-age males (age: 23 +/- 1 years, height: 176 +/- 4 cm, weight: 76 +/- 6 kg). The primary intention of this study was to determine if arm unloading is an effective analogue for simulating the effects of weightlessness on human skeletal muscle. Subjects were tested 2-3 days preceding unloading in a standard arm sling and following removal of the sling. The sling was worn during waking hours to unload the arm. Subjects were allowed to remove the sling during sleep and bathing. Torque production (Nm) during maximal isometric extension at 90 degrees significantly declined (P < 0.05) in response to unloading (53.93 +/- 5.07 to 47.90 +/- 5.92; 12%). There was no significant change (P > 0.05) in the force-velocity attributes of the triceps over the other measured velocities (1.05, 1.57, 2.09, 3.14, 4.19, 5.24 rad.s-1). Cross-sectional muscle area (CSA) of the upper arm was smaller (44.3 +/- 2.7 to 42.4 +/- 2.5 cm2; 4%) following 4 weeks of unloading (P < 0.05). Histochemical analysis of individual muscle fibres demonstrated reductions in fibre CSA of 27 and 18% for type I and type II fibres, respectively. However, these changes were not statistically significant. Electrophoretic analysis of muscle samples revealed a significant increase (40 +/- 7 to 58 +/- 4%, pre- and post-, respectively) in myosin heavy chain (MHC) type II isoforms following unloading. Reductions in type I MHC isoform composition failed to reach statistical significance (P < 0.08). Amplitude of the integrated electromyographic (IEMG) signal during maximal isometric contraction of the long head of the triceps decreased by 21% in response to the 4-week unloading period (P < 0.05). The changes in triceps, muscle structure and function found with arm unloading are similar in magnitude and direction to data obtained from humans following exposure to real and simulated weightlessness. These findings demonstrate that arm unloading produces some of the effects seen in response to weightlessness in muscles of the upper arm and provides potential for an additional model to simulate the effects of microgravity on human skeletal muscle.

The purpose of this study was to examine myosin heavy chain (MHC) and myosin light chain (MLC) isoforms following 12 wk of progressive resistance training (PRT). A needle biopsy was taken from the vastus lateralis to determine fiber-type expression [ATPase (pH 4.54) and MHC/MLC] in seven healthy men (age = 74.0 +/- 1.8 yr). Subjects were also tested for 1-repetition maximum (1-RM), pre- and posttraining. The progressive knee extensor protocol consisted of three sets at 80% of 1-RM 3 days/wk for 12 wk. Freeze-dried, single muscle fibers were dissected for MHC and MLC analysis and then subjected to SDS-PAGE and silver staining, pre- and posttraining. MHC expression increased in the I (10.4%; P < 0.05) and decreased in I/IIa (9.0%; P < 0.05), I/IIa/x (0.9%; P < 0.05), and IIa/x (8.9%; P < 0.05) isoforms, with no change in the IIa and IIx isoforms, pre- vs. posttraining (total fibers = 3,059). The MLC(3f)-to-MLC(2) ratio did not change with the PRT in either the MHC I or MHC IIa isoforms (total fibers = 902), pre- to posttraining. ATPase fiber distribution did not significantly differ following training (I: 50. 4 +/- 6.7 vs. 51.9 +/- 7.9, IIa: 36.8 +/- 5.3 vs. 41.1 +/- 7.0, IIb: 12.8 +/- 5.6 vs. 7.0 +/- 4.0%; pre- vs. posttraining, respectively). 1-RM increased (51.9%; P < 0.05) from pre- to posttraining. The PRT provide a stimulus for alterations in MHC isoforms, which demonstrated a decrease in all hybrid isoforms and an increase in MHC I expression (not found in the ATPase results), unlike the MLC ratio (3:2), which was not altered with training.

The purpose of this investigation was to determine the effects of postexercise eucaloric carbohydrate-protein feedings on muscle glycogen restoration after an exhaustive cycle ergometer exercise bout. Seven male collegiate cyclists [age = 25.6 +/- 1.3 yr, height = 180.9 +/- 3.2 cm, wt = 75.4 +/- 4.0 kg, peak oxygen uptake (VO(2 peak)) = 4.20 +/- 0.2 l/min] performed three trials, each separated by 1 wk: 1) 100% alpha-D-glucose [carbohydrate (CHO)], 2) 70% carbohydrate-20% protein (PRO)-10% fat, and 3) 86% carbohydrate-14% amino acid (AA). All feedings were eucaloric, based on 1.0 g. kg body wt(-1). h(-1) of CHO, and administered every 30 min during a 4-h muscle glycogen restoration period in an 18% wt/vol solution. Muscle biopsies were obtained immediately and 4 h after exercise. Blood samples were drawn immediately after the exercise bout and every 0.5 h for 4 h during the restoration period. Increases in muscle glycogen concentrations for the three feedings (CHO, CHO-PRO, CHO-AA) were 118 mmol/kg dry wt; however, no differences among the feedings were apparent. The serum glucose and insulin responses did not differ throughout the restoration period among the three feedings. These results suggest that muscle glycogen restoration does not appear to be enhanced with the addition of proteins or amino acids to an eucaloric CHO feeding after exhaustive cycle exercise.

1769 The intent of this investigation was to examine the quantitative alterations in neuromuscular drive (Electromyography) during submaximal and maximal intensities, as well as changes in cross sectional area (CSA) and functional ability during a 12-week bilateral knee extensor resistance training program (RTP). The RTP consisted of 2 sets of 10 repetitions, and a third set to volitional exhaustion at 80% 1RM, 3 days/week for 12 weeks. Ten healthy men (70.8±1.5yrs, 80.28±3.6kg, 174.5±2.1 cm) were evaluated for submaximal and maximal isometric electromyography (EMG), bilateral 1-repitition maximum (1RM), and whole muscle CSA of the right mid-thigh by computed tomography (CT), pre-and-post RTP. Isometric EMG of the v. lat and v. med was performed at 27 N·m and 55 N·m workloads, at 30°-knee extension. 1RM strength and CSA increased pre-to-post-training 57±5% and 7±1%, respectively. Submaximal EMG (expressed as a % of MVC EMG) for the v. med. and v. lat. decreased 35±7% and a 12±7% at 27 N·m and 36±7% and 27±8% at 55 N·m, respectively. The post-training maximal isometric EMG increased 58±26% for the v. med. and 30±5% for the v. lat. All data above are statistically significant (p<0.05), with the exception of the submaximal EMG v. lat. at 27 N·m. Torque/EMG was similar in v. med. (11±9% Δ) and v. lat. (5±5% Δ). A comparison of torque/CSA revealed a 14±3% increase pre-to-post training (p>0.05). In conclusion, the training increased 1RM strength, CSA, maximal EMG, while submaximal EMG decreased. In addition, the commensurable changes of torque with EMG and CSA suggest that hypertrophy and neural drive did not account for all of the increases in muscle strength. Supported by NIH grant AG154876

The extent to which there is a prolonged elevation in metabolic rate, after resistance exercise, is unclear. The purpose of this study was to assess whether a single bout of resistance exercise can alter basal metabolic rate(BMR) in healthy older men with normal glucose tolerance (n=6; age 66±5 yr; weight 80.4±8.8 kg; BMI 26.2±1.4 kg·m-2; body fat 23.4±3.0%). BMR was measured on two separate occasions, once after a non-exercise control period and again 48 hours after a bout of resistance exercise. The exercise bout consisted of single-leg knee extensions (right and left leg) and chest press (16 sets, 10 repetitions/set) at 75% of the individual's 3 repetition maximum. Subjects only performed the concentric phase of the lift. To control diet and activity subjects resided in the General Clinical Research Center for a 3 day period during each measurement. The subjects were provided a eucaloric diet (15% protein, 60% carbohydrate, 25% fat) and did not exercise prior to the control measurement, or during the 48 hours after the resistance exercise bout. BMR was measured 12 hours post-absorptive. Subjects were awakened, voided, were weighed and then reclined in bed for a continuous 30 min breath collection using a flow through hood system (Hartmann and Braun O2 and CO2 analyzers). VO2;L/min) was higher (p<0.05) 48 hours after the exercise bout(.242±0.03) compared to the control measure (.235±0.03). Extrapolated over a 24-hour periód, thé energy expenditure corresponded to 1789±36 and 1692±77 kcals for the exercise and control measures, respectively. We conclude that an acute bout of resistance exercise causes an increase in BMR in healthy older males for up to 48 hours after exercise.

Perfluorosulfonic acid materials such as Nafion(1) that have been exchanged with Ag(I) ion have been shown to exhibit high selectivities with respect to membrane separations of mixtures of unsaturated organic compounds. This unusual behavior cannot be explained solely by the interaction of the unsaturate with Ag(I) ion. The membrane morphology appears to also contribute to the observed selectivities, To better understand the connection between morphology and membrane selectivity, Nafion materials with equivalent weights (EW) ranging from 1100 to 1500 g/equiv were characterized through their uptake of water and through small-angle X-ray scattering (SAXS) studies for materials in the dry, Ag+ forms and hydrated, Na+-forms. The water contents decreased with increasing EW from 34% to 10%. The SAXS data indicated that the ionic cluster sizes were similar (1.6 +/- 0.1 nm) for the different materials in their dry, Ag+ forms but decreased slightly with increasing EW in the hydrated forms from 4.4 to 3.6 nm. Fluxes of 1,5-hexadiene and 1-hexene through the hydrated Ag+ forms of these materials decreased with increasing EW, but both the ideal and observed separation factors, while different, maintain approximately the same values for each membrane evaluated. The amount of alkenes absorbed into these materials from single-component or mixed feed solutions per mol of Ag+ sites was virtually the same for all materials. This result appears to be the basis for the observed high selectivities. Calculations based on the water contents and SAXS data show that for the series of Nafion materials the distances between ionic clusters vary by only 6% for the dry membranes and by only 3% for the hydrated membranes.

The dependence of the cloud fraction on horizontal resolution is explored with the National Center for Atmospheric Research Community Climate Model (CCM1). Using R15, T42, T63 and T106 versions of the CCM, we find that the total cloud amount monotonically decreases with increased horizontal resolution. This decrease is particularly evident in the low‐level cloud associated with stable condensation in the tropics. Decreases in low‐level and upper‐level extratropical clouds with increased resolution are also apparent. Analysis of these model simulations shows that this decrease is due to increased advective drying of the lower atmosphere by stronger subsidence. Stronger upward motion which is directly associated with stronger heating in the convergence region by moist convective adjustment and stable condensation processes is also apparent with increased horizontal resolution. This stronger upward motion affects the upper tropical cloud amount. The upper‐level extra‐tropical cloud amount is shown to depend strongly on the correction applied to the spectral transport of moisture in the model, the so‐called “q fixer” which eliminates negative moisture. At higher resolution this spectral filler plays less of a role at the poles than at the lower resolutions. This study has important implications for the parameterization of cloud activity in large‐scale models, since a certain resolved large‐scale circulation is necessary for embedding these cloud parameterizations. It also raises questions relating to scale dependence of cloud and precipitation parameterizations.