Unilateral Exercise Research Articles

Tart cherry concentrate does not enhance muscle protein synthesis response to exercise and protein in healthy older men.

Oxidative stress and inflammation may contribute to anabolic resistance in response to protein and exercise in older adults. We investigated whether consumption of montmorency cherry concentrate (MCC) increased anabolic sensitivity to protein ingestion and resistance exercise in healthy older men. Sixteen healthy older men were randomized to receive MCC (60 mL·d-1) or placebo (PLA) for two weeks, after baseline measures in week 1. During week 3, participants consumed 10 g whey protein·d-1 and completed three bouts of unilateral leg resistance exercise (4 × 8-10 repetitions at 80% 1RM). Participants consumed a bolus (150 mL) and weekly (50 mL) doses of deuterated water. Body water 2H enrichment was measured in saliva and vastus lateralis biopsies were taken from the non-exercised leg after weeks 1, 2 and 3, and the exercised leg after week 3, to measure tracer incorporation at rest, in response to protein and protein + exercise. Myofibrillar protein synthesis increased in response to exercise + protein compared to rest (p < 0.05) in both groups, but there was no added effect of supplement (MCC: 1.79 ± 0.75 EX vs 1.15 ± 0.40 rest; PLA: 2.22 ± 0.54 vs 1.21 ± 0.18; all %·d-1). Muscle total NFĸB protein was decreased with exercise and protein in MCC (NFĸB: -20.7 ± 17.5%) but increased in PLA (NFĸB: 17.8 ± 31.3%, p = 0.073). Short-term MCC ingestion does not affect the anabolic response to protein and exercise in healthy, relatively active, older men, despite MCC ingestion attenuating expression of proteins involved in the muscle inflammatory response to exercise, which may influence the chronic training response.

The effect of eccentric exercise and delayed onset muscle soreness on the homologous muscle of the contralateral limb

High intensity eccentric exercise induces muscle fiber damage and associated delayed-onset muscle soreness (DOMS) resulting in an impaired ability of the muscle to generate voluntary force. This study investigates the extent to which DOMS, induced by high intensity eccentric exercise, can affect the activation and performance of the non-exercised homologous muscle of the contralateral limb. Healthy volunteers performed maximal voluntary contractions of knee extension and sustained isometric knee extension at 50% of maximal force until task failure on both the ipsilateral exercised limb and the contralateral limb. Surface electromyography (EMG) was recorded from the ipsilateral and contralateral knee extensor muscles (vastus medialis, rectus femoris, and vastus lateralis). Maximal isometric knee extension force (13.7% reduction) and time to task failure (38.1% reduction) of the contralateral non-exercised leg decreased immediately after eccentric exercise, and persisted 24 h and 48 h later (p < 0.05). Moreover, the amplitude of muscle activity recorded from the contralateral knee extensor muscles was significantly lower during the post exercise maximal and submaximal contractions following high intensity eccentric exercise of the opposite limb (p < 0.05). Unilateral high intensity eccentric exercise of the quadriceps can contribute to reduced neuromuscular activity and physical work capacity of the non-exercised homologous muscle in the contralateral limb.

Hemodynamic response to unilateral resistance exercise with lactotripeptides

Hemodynamic response to unilateral resistance exercise with lactotripeptides

Triceps Brachii Muscle Strength and Architectural Adaptations with Resistance Training Exercises at Short or Long Fascicle Length

The aim of this study was to investigate whether resistance training at short or long triceps brachii fascicle length induces different muscular strength and architectural adaptations. Nine young, novice, female participants, were trained for 6 weeks (two sessions/week) performing 6 sets × 6-RM (repetition maximum) unilateral cable exercises either with push-downs at short fascicle length (S) or overhead extensions with the contralateral arm at long fascicle length (L) of triceps brachii. Before and after training, 1-RM elbow extension and triceps brachii muscle architecture were evaluated. Muscle architecture was analyzed at 50% and 60% of the upper-arm length. Two-dimensional longitudinal muscle area of the triceps long head was also analyzed. The results indicated that 1-RM increased 40.1 ± 21.3% and 44.5 ± 20.1% (p &lt; 0.01) after S and L, respectively. Muscle thickness at 50% length was increased 10.7 ± 15.3% (p &lt; 0.05) and 13.7 ± 9.0% (p &lt; 0.01) after S and L, while at 60% it was increased 15.5 ± 18.8% (p &lt; 0.05) and 19.4 ± 16.3% (p &lt; 0.01), respectively. Longitudinal muscle area increased similarly after S and L (p &lt; 0.01). Fascicle angle and length were not altered with training. These results indicate that muscle strength and architecture of elbow extensors adapt similarly during the first six weeks of resistance training at either long or short fascicle length.

Achilles tendon loading during weight bearing exercises

ObjectiveCompare the estimated Achilles tendon (AT) loading using a musculoskeletal model during commonly performed weight bearing therapeutic exercises. DesignControlled laboratory study. SettingUniversity biomechanics laboratory. ParticipantsEighteen healthy males (Age:22.1 ± 1.8 years, height:177.7 ± 8.4 cm, weight = 74.29 ± 11.3 kg). Main outcome measure(s)AT loading was estimated during eleven exercises: tandem, Romberg, and unilateral standing, unilateral and bilateral heel raising, unilateral and bilateral jump landing, squat, lunge, walking, and running. Kinematic and kinetic data were recorded at 180 Hz and 1800 Hz respectively. These data were then used in a musculoskeletal model to estimate force in the triceps surae. AT cross-sectional images were measured by ultrasound to determine AT stress. A repeated measure multivariate analysis of variance (α = 0.05) was used on AT loading variables. ResultsSquat and unilateral jump landing were the most different in AT stress. Peak AT stress variables were generally greater during more dynamic, unilateral exercises compared to more static, bilateral exercises. ConclusionsBilateral, more static exercises resulted in less AT loading and may serve as a progression during the rehabilitation compared to more dynamic, unilateral exercises.

Cardiovascular Responses During Resistance Exercise in Patients With Parkinson Disease

BackgroundPatients with Parkinson disease (PD) present cardiovascular autonomic dysfunction that impairs blood pressure control. However, cardiovascular responses during resistance exercise are unknown in these patients. ObjectiveTo investigate cardiovascular responses during resistance exercise performed with different muscle masses in patients with PD. DesignProspective, repeated-measures. SettingExercise Hemodynamic Laboratory, School of Physical Education and Sport, University of São Paulo. ParticipantsThirteen patients with PD (4 women, 62.7 ± 1.3 years, stages 2-3 of the modified Hoehn and Yahr scale; “on” state of medication) and 13 paired control patients without PD (7 women, 66.2 ± 2.0 years). InterventionsBoth groups performed, in a random order, bilateral and unilateral knee extension exercises (2 sets, 10-12 maximal repetition, 2-minute intervals). Main Outcome MeasurementsSystolic blood pressure (SBP) and heart rate (HR) were assessed before (pre) and during the exercises. ResultsIndependent of set and exercise type, SBP and HR increases were significantly lower in PD than the control group (combined values: +45 ± 2 versus +73 ± 4 mm Hg and +18 ± 1 versus +31 ± 2 bpm, P = .003 and .007, respectively). Independently of group and set, the SBP increase was greater in the bilateral than the unilateral exercise (combined values: +63 ± 4 versus +54 ± 3 mm Hg, P = .002), whereas the HR increase was similar. In addition, independently of group and exercise type, the SBP increase was greater in the second than the first set (combined values: +56 ± 4 versus +61 ± 4 mm Hg, P = .04), whereas the HR increases were similar. ConclusionsPatients with PD present attenuated increases in SBP and HR during resistance exercise in comparison with healthy subjects. These results support that resistance exercise is safe and well tolerated for patients with PD from a cardiovascular point of view supporting its recommendation for this population. Level of EvidenceII

Effect of Sexual Intercourse on Lower Extremity Muscle Force in Strength-Trained Men

BackgroundSex has been deemed taboo for athletic performance going back to ancient Rome and Greece, as the act of sex was thought to promote ease and a sense of relaxation. AimThis study examined the effect of sexual intercourse completed 12 hours before a bout of isokinetic dynamometry on muscle force production in strength-trained men. Methods12 Healthy physically active men (age = 25.6 ± 3.8 years) who were sexually active participated in this study. After men completed a familiarization session on day 1, muscle force was measured during 5 sets of maximal unilateral knee extension (KE) and knee flexion exercise at 30 deg/s after men engaged in or abstained from sexual intercourse within the previous 12 hours. The order of this treatment was randomized across participants, and time of day was maintained across all sessions. OutcomesLower extremity muscle strength and endurance were measured. ResultsData showed no significant effect (P = .34 and P = .39) of sexual intercourse on peak or average KE or knee flexion torque. For example, after sexual intercourse, KE torque was similar in set 1 (198.9 ± 39.1 ft/lb vs 190.2 ± 28.7 ft/lb) and set 5 (163.2 ± 30.8 ft/lb vs 159.4 ± 35.2 ft/lb) compared to when men abstained from sexual intercourse. Clinical TranslationEngaging in sexual intercourse on the night before exercise is not detrimental to muscular strength in active men. ConclusionsThis study is strengthened by use of a homogeneous sample of active men as well as precise determination of changes in muscle function via isokinetic dynamometry. However, completion of sexual intercourse was confirmed through self-report rather than direct observation, so it is not certain if participants actually met the requirements of each condition. Results demonstrate that sexual intercourse does not significantly impact lower extremity muscle force, which suggests that restricting sexual activity before short-term, high-force activity is unnecessary.Valenti LM, Suchil C, Beltran G, et al. Effect of Sexual Intercourse on Lower Extremity Muscle Force in Strength-Trained Men. J Sex Med 2018;15:888–893.

Moderately heavy exercise produces lower cardiovascular, RPE, and discomfort compared to lower load exercise with and without blood flow restriction.

To determine the acute cardiovascular and perceptual responses of low-load exercise with or without blood flow restriction and compare those responses to that of moderately heavy exercise. Twenty-two participants completed unilateral elbow flexion exercise with a moderately heavy-load- [70% one-repetition maximum (1RM); 70/0] and with three low-load conditions (15% 1RM) in combination with 0% (15/0), 40%, (15/40) and 80% (15/80) arterial occlusion pressure. Participants exercised until failure (or until 90 repetitions per set). The cardiovascular response (arterial occlusion) was measured pre and post exercise and the perceptual responses [ratings of perceived exertion (RPE) and discomfort] were determined before and after each set of exercise. For arterial occlusion pressure, the lower-load conditions had greater change from pre to post compared to 70/00 (e.g., 15/80: 44 vs. 70/0: 34mmHg). RPE was highest across the sets for the 15/80 condition with the other conditions having similar RPE (e.g., set 4: median rating of 17.2 for 15/80 vs. ~ 15.5 for other conditions). Ratings of discomfort were also greatest for the 15/80 condition (15/80 > 15/40 > 15/0 > 70/0). Exercise volume within the 15/0 and 15/40 conditions were similar but were significantly greater than that observed with the 15/80 and 70/0 conditions. Low-load exercise to volitional failure results in a greater cardiovascular response to that of moderately heavy-load exercise. When high pressure is applied to low load exercise, there is a reduction in exercise volume but an elevated perceptual response that may be an important consideration when applying this stimulus in practice.

Could Knee Extension And Leg Press Exercises Induce Different Time Course Of Muscle Recovery?

Single- (SJ) and multiple-joint (MJ) resistance exercises are recommended for strength and hypertrophic gains. However, the levels of mechanical strain and hence muscle damage may be distinct between MJ and SJ resistance exercises. Studies comparing symptoms of muscle damage following MJ and SJ exercises are lacking. PURPOSE: This study investigated the time course of symptoms of muscle recovery after two knee extension exercises in resistance-untrained men. METHODS: Seven men (25 ± 4 yrs) were randomly assigned to perform a unilateral MJ multi-joint resistance exercise (i.e. leg press, LP) and a unilateral single-joint resistance exercise (i.e. seated knee extension, KE) with the contralateral limb. Participants performed 8 sets of 10 repetition maximum of both exercises with 2 min rest between sets. Muscle edema (ME), peak torque (PT), 1-legged countermovement (CMJ), and muscle soreness (MS) were measured pre, post, 24, 48, 72 and 96h following exercise. RESULTS: ME of the rectus femoris returned to baseline at 48h after LP exercise, and at 24h after the KE exercise. ME of the vastus lateralis recovered at 24h after both exercises. PT recovered at 24h, and there was no difference between both exercises (p>0.05). CMJ returned to the baseline values 72h after the LP exercise, and 24h after the KE exercise. Muscle soreness of the rectus femoris was greater at 48h after KE when compared to LP exercise. There was no difference between exercises in the magnitude of MS response in vastus lateralis (p>0.05). CONCLUSIONS: Resistance-untrained men experience different muscle recovery following LP and KE exercises. The MJ condition was more stressful for knee extensors muscles than SJ, taking more time to recover from muscle damage.

Blunted Muscle Protein Synthetic Response To Feeding And Resistance Exercise In Obese Young Adults

Obesity induces anabolic resistance of myofibrillar protein synthesis rates (MPS) to the ingestion of a protein-dense food in young adults. However, the effectiveness of acute resistance exercise before food ingestion to enhance the amino acid sensitivity of MPS with obesity has not been examined. PURPOSE: To compare the impact of resistance exercise on MPS responses to protein-dense food ingestion in normal-weight (NW) and obese (OB) young adults. METHODS: 7 NW (21±1y, BMI 21.9±0.5 kg/m2) and 7 OB (22±1y, BMI 35.7±2.3 kg/m2) men and women underwent primed continuous L-[ring-13C ]phenylalanine infusions coupled with blood and muscle biopsy collections to measure MPS at basal and fed-state of the exercise (EX) and non-exercise (CON) legs. Participants performed unilateral resistance exercise (4 sets × 10-12 repetitions) followed by the ingestion of 6 oz of lean pork loin (36 g protein; 4 g fat; 180 kcal). RESULTS: Total work performed during exercise was similar among groups (NW: 1610±164 kg; OB: 1888±154 kg, P=0.24). Plasma essential amino acid concentrations increased similarly after pork ingestion in both groups (time effect: P<0.05) with peak values at 2 h of the postprandial period. Basal MPS was similar between NW and OB groups (P>0.05). MPS was stimulated in the EX and CON legs after pork ingestion in both the NW (absolute change from basal: CON 0.027±0.008 %/h; EX 0.058±0.011 %/h) and OB groups (CON 0.027±0.006 %/h; EX 0.033±0.011 %/h; P<0.05). MPS was stimulated to a greater extent in the EX vs. CON legs in NW (P=0.02) but not OB group (P=0.26). CONCLUSION: Our results suggest that increased adiposity may attenuate the effectiveness of resistance exercise to augment the postprandial MPS response. Funding provided by the ACSM Foundation Doctoral Student Research Grant

Resistance Exercise and Low Dose Protein Ingestion Augments Anabolic Signaling Mechanisms In Older Women

Resistance exercise enhances skeletal muscle anabolic signaling responses to the ingestion of sub-optimal amounts of protein in young men. However, the effectiveness of resistance exercise to potentiate the phosphorylation of the mechanistic target of rapamycin (mTORC1) to the ingestion of minimal amount of protein in aging women has not been well characterized. PURPOSE: We compared the phosphorylated-state ofmTORC1 before and after ingestion of ~14 g whey protein or water at rest and after resistance exercise in middle-aged and older women. METHODS: 10 women (59±2 y; BMI: 25±1 kg/m2; LBM: 46±2 kg) performed a bout of unilateral leg extension exercise (3 sets × 12 repetitions at 60% estimated 1RM) prior to ingesting whey protein (0.3g/kg LBM; WHEY, n=5) or water (WATER n=5). Blood and skeletal muscle biopsies were used to measure plasma amino acids and insulin concentrations and phosphorylation of mTORC1 at Ser2448 at 2 and 4 h of the postprandial phase in both exercise (EX) and non-exercised (CON) legs. RESULTS: Plasma branched chain amino acid concentrations were increased from basal (2.5-fold) in WHEY (P<0.05), but not in WATER condition (P>0.05). Plasma insulin concentrations increased after WHEY (2.3±0.8 fold change from basal, P=0.02), but not after WATER ingestion (1.0 ± 0.1 fold-change, P=0.45). WHEY ingestion increased mTORC1 phosphorylation at 2 h (3.4±0.6 and 1.7±0.3 fold-change in EX and CON, respectively P<0.05). There were no changes in mTORC1 phosphorylation after WATER ingestion at any time point (P>0.05). CONCLUSION: Our data demonstrated that consuming a minimal amount of protein immediately after resistance exercise resulted in a greater, but transient, phosphorylation of anabolic signaling mechanisms involved in protein translation over that induced by feeding or resistance exercise alone.

UNILATERAL AND BILATERAL EXERCISE MOVEMENTS

Apply It! By reading this article, the health and fitness professional will: Understand neurophysiological concepts such as the bilateral deficit, bilateral facilitation, and cross-education effect and extend their potential applications to exercise prescription Prescribe bilateral and unilateral exercises for the appropriate clientele based on an evidence-based rationale

Interface pressure, perceptual, and mean arterial pressure responses to different blood flow restriction systems.

This study examined the cuff to limb interface pressure during blood flow restriction (BFR), and the perceptual and mean arterial pressure responses, in different BFR systems. Eighteen participants attended three experimental sessions in a randomised, crossover, counterbalanced design. Participants underwent inflations at 40% and 80% limb occlusive pressure (LOP) at rest and completed 4 sets of unilateral leg press exercise at 30% of one repetition maximum with BFR at 80% LOP. Different BFR systems were used each session: an automatic rapid-inflation (RI), automatic personalized tourniquet (PT) and manual handheld pump and sphygmomanometer (HS) system. Interface pressure was measured using a universal interface device with pressure sensors. Perceived exertion and pain were measured after each set, mean arterial pressure (MAP) was measured pre-, 1-minute post- and 5-minutes post-exercise. Interface pressure was lower than the set pressure in all BFR systems at rest (P<.05). Interface pressure was, on average, 10±8 and 48±36mm Hg higher than the set pressure in the RI and HS system (P<.01), with no differences observed in the PT system (P>.05), during exercise. Pain and exertion were greater in sets 3 and 4 in the RI and HS system compared to the PT system (P<.05). MAP was higher in the RI and HS system compared to the PT system at 1-minute and 5-minutes post-exercise (P<.05). BFR systems applying higher pressures amplify mean arterial pressure and perceptual responses. Automatic BFR systems appear to regulate pressure effectively within an acceptable range during BFR exercise.

Conduit Artery Diameter During Exercise Is Enhanced After Local, but Not Remote, Ischemic Preconditioning.

Introduction: The ability of ischemic preconditioning (IPC) to enhance exercise capacity may be mediated through altering exercise-induced blood flow and/or vascular function. This study investigated the hypothesis that (local) IPC enhances exercise-induced blood flow responses and prevents decreases in vascular function following exercise.Methods: Eighteen healthy, recreationally trained, male participants (mean ±SD: age 32 ± 8 years; BMI 24.2 ± 2.3; blood pressure 122 ± 10/72 ± 8 mmHg; resting HR 58 ± 9 beats min-1) received IPC (220 mmHg; 4 × 5-min bilateral arms), REMOTE IPC (220 mmHg; 4 × 5-min bilateral legs), or SHAM (20 mmHg; 4 × 5-min bilateral arms) in a counterbalanced order prior to 30-min of submaximal (25% maximal voluntary contraction) unilateral rhythmic handgrip exercise. Brachial artery diameter and blood flow were assessed every 5-min throughout the 30-min submaximal exercise using high resolution ultrasonography. Pre- and post-exercise vascular function was measured using flow-mediated dilation (FMD).Results: IPC resulted in enlarged brachial artery diameter during exercise [0.016 cm (0.003–0.03 cm), P = 0.015] compared to REMOTE IPC, but blood flow during exercise was similar between conditions (P > 0.05). Blood flow (l/min) increased throughout exercise (time: P < 0.005), but there was no main effect of condition (P = 0.29) or condition ∗ time interaction (P = 0.83). Post-exercise FMD was similar between conditions (P > 0.05).Conclusion: Our data show that local (but not remote) IPC, performed as a strategy prior to exercise, enhanced exercise-induced conduit artery diameter dilation, but these changes do not translate into increased blood flow during exercise nor impact post-exercise vascular function.

High-intensity handgrip training lowers blood pressure and increases heart rate complexity among postmenopausal women: a pilot study.

Handgrip exercise is an emerging strategy for resting blood pressure (BP) reduction requiring minimal time and exercise effort. However, the research literature is currently limited to handgrip protocol designs predominantly prescribing sustained grip contractions, with little assessment of alternative options. Furthermore, our understanding of the utility of handgrip exercise would be strengthened by an evaluation of the physiological mechanisms driving BP reductions and an assessment of the interindividual response variability. As such, this research was designed to perform an initial evaluation of the pragmatic effectiveness of a novel at-home, high-intensity, unilateral (nondominant) handgrip exercise training program in reducing resting BP, while simultaneously exploring mediators of BP change including a neurocardiac index of autonomic nervous control [heart rate (HR) variability], measures of arterial stiffness (radial augmentation index and carotid-radial pulse wave velocity), and cardiovascular reactivity to psychophysiological stressors. Postmenopausal women were recruited to complete 8 weeks of handgrip exercise training. Aforementioned measures of resting BP and mediators of BP change were acquired at the midway point and end of training. All participants (n=17) completed training with high self-reported adherence (96.9%) and improvement in grip strength (2.7±2.4kg, P<0.05). Handgrip training reduced resting systolic BP (-5.1±7.7 mmHg, P<0.05) and improved HR complexity (sample entropy: 0.24±0.31, P<0.05), without significant changes to resting diastolic BP, HR, or arterial stiffness (all P>0.05). This pilot study successfully shows the potential utility of high-intensity intermittent handgrip exercise for improvements in cardiovascular health among postmenopausal women, with additional research required to further explore the underlying physiological mechanisms driving such improvements.

Comparison of different regression models to fit the force–velocity relationship of a knee extension exercise

The aims of this study were to compare the goodness of fit and the concurrent validity of three regression models of the force–velocity relationship in a unilateral knee extension exercise. The force–velocity relationship and the one-repetition-maximum load in the dominant and non-dominant leg were obtained in 24 male sports sciences students by a progressive protocol. Additionally, the maximum voluntary contraction (MVC) of the knee extensor muscles was recorded. Individual force–velocity relationships were obtained by the linear, quadratic polynomial and exponential regression models. Although the adjusted coefficients of determination of all three models were high, the polynomial model’s coefficient was slightly but significantly higher than the rest of the models (p < 0.05), while the standard error of estimate was slightly higher for the linear than for polynomial model (p = 0.001). MVC was underestimated by F 0 calculated from the linear and polynomial models, while the maximum power was accurately estimated by the linear model. In summary, while the polynomial model revealed somewhat better fit, the linear model more accurately estimates the maximum power and provides the parameters of apparent physiological meaning. Therefore, we recommend using the linear model in research and routine testing of mechanical capacities of knee extensors.

Hegemony and the politics of education in Hong Kong: from the post-war era to the post-handover era

ABSTRACT The process of Chinese nation-building in education reveals the hegemonic strategies of the colonial power and the adaptation of indigenous forces when Hong Kong was undergoing decolonisation and the transfer of sovereignty. The return of Hong Kong to Chinese sovereignty has been a crucial indicator for the potential re-unification of China, as it presents a model for the possible future reintegration of Taiwan. The idea of hegemony applies to different dominant groups in the two periods under review. In the first period, London attempted to influence the development of groups in Hong Kong and incorporate them into the colonial programme. In the second period, Beijing attempts to influence groups in Hong Kong facilitate the reintegration of Hong Kong into a larger Chinese identity. Yet, it is far too simple to picture a unilateral exercise of power by an identifiable centre and consider the periphery as mere objects of successful manipulation by the centre. Continued study of the evolution of nation-building in education, under the influence of a series of complex and shifting factors of the Hong Kong society, will be enlightening for the comprehension of the ever-changing and increasingly complicated political culture.

Even effect of milk protein and carbohydrate intake but no further effect of heavy resistance exercise on myofibrillar protein synthesis in older men.

The responsiveness of older individuals' skeletal muscle to anabolic strategies may be impaired. However, direct comparisons within the same experimental setting are sparse. The aim of this study was to assess the resting and post-resistance exercise muscle protein synthesis rates in response to two types of milk protein and carbohydrate using a unilateral exercise leg model. Twenty-seven older (69 ± 1year, mean ± SE) men were randomly assigned one of three groups: Whey hydrolysate (WH), caseinate (CAS), or carbohydrate (CHO). By applying stable isotope tracer techniques (L-[15N]phenylalanine), the fasted-rested (basal) myofibrillar fractional synthesis rate (FSR) was measured. Hereafter, FSR was measured in the postprandial phase (0.45g nutrient/kg LBM) in both legs, one rested (fed-rest) and one exercised (10 × 8 reps at 70% 1RM; fed-exercise). In addition, the activity of p70S6K and venous plasma insulin, phenylalanine, and leucine concentrations were measured. Insulin, phenylalanine, and leucine concentrations differed markedly after intake of the different study drinks. The basal FSR in WH, CAS, and CHO were 0.027 ± 0.003, 0.030 ± 0.003, and 0.030 ± 0.004%/h, the fed-rested FSR were 0.043 ± 0.004, 0.045 ± 0.003, and 0.035 ± 0.004%/h, and the fed-exercised FSR were 0.041 ± 0.004, 0.043 ± 0.004, and 0.034 ± 0.004%/h, respectively. No significant differences were observed at any state between the groups. Fed-rested- and fed-exercised FSR were higher than basal (P < 0.001). 3h after exercise and feeding, no significant group differences were detected in the activity of p70S6K. Milk protein and carbohydrate supplementation stimulate myofibrillar protein synthesis in older men, with no further effect of heavy resistance exercise within 0-3h post exercise.

Protein leucine content is a determinant of shorter- and longer-term muscle protein synthetic responses at rest and following resistance exercise in healthy older women: a randomized, controlled trial

Older women may not be consuming enough protein to maintain muscle mass. Augmentation of protein intake with leucine may enhance the muscle protein synthetic response in older women to aid in maintaining muscle mass. We measured the acute (hourly) and integrated (daily) myofibrillar protein synthesis (myoPS) response to consumption of a high-quality mixed protein beverage compared with an isonitrogenous protein beverage with added leucine. In a parallel design, free-living, healthy older women (aged 65-75 y, n = 11/group) consumed a fixed, weight-maintaining diet with protein at 1.0 g · kg-1 · d-1 and were randomly assigned to twice-daily consumption of either 15 g milk protein beverage containing 4.2 g leucine (LEU) or 15 g mixed protein (milk and soy) beverage containing 1.3 g leucine (CON). Unilateral leg resistance exercise allowed a determination of acute ([13C6]-phenylalanine infusion, hourly rate) and integrated (deuterated water ingestion, daily rate) exercised and rested myoPS responses. Acute myoPS increased in response to feeding in the rested (CON: 13% ± 4%; LEU: 53% ± 5%) and exercised (CON: 30% ± 4%; LEU: 87% ± 7%) leg in both groups, but the increase was greater in LEU (P < 0.001). Integrated myoPS increased during the supplementation period in both legs (rested: 9% ±1%; exercised: 17% ± 2%; P < 0.001) in LEU, but in the exercised leg only (7% ± 2%; P < 0.001) in CON. A 15-g protein-containing beverage with ∼4 g leucine induced greater increases in acute and integrated myoPS than did an isonitrogenous, isoenergetic mixed-protein beverage. Declines in muscle mass in older women may be attenuated with habitual twice-daily consumption of a protein beverage providing 15 g protein and higher (4.2 g/serving) amounts of leucine. This trial was registered at clinicaltrials.gov as NCT02282566.

The Importance of Muscular Strength: Training Considerations.

This review covers underlying physiological characteristics and training considerations that may affect muscular strength including improving maximal force expression and time-limited force expression. Strength is underpinned by a combination of morphological and neural factors including muscle cross-sectional area and architecture, musculotendinous stiffness, motor unit recruitment, rate coding, motor unit synchronization, and neuromuscular inhibition. Although single- and multi-targeted block periodization models may produce the greatest strength-power benefits, concepts within each model must be considered within the limitations of the sport, athletes, and schedules. Bilateral training, eccentric training and accentuated eccentric loading, and variable resistance training may produce the greatest comprehensive strength adaptations. Bodyweight exercise, isolation exercises, plyometric exercise, unilateral exercise, and kettlebell training may be limited in their potential to improve maximal strength but are still relevant to strength development by challenging time-limited force expression and differentially challenging motor demands. Training to failure may not be necessary to improve maximum muscular strength and is likely not necessary for maximum gains in strength. Indeed, programming that combines heavy and light loads may improve strength and underpin other strength-power characteristics. Multiple sets appear to produce superior training benefits compared to single sets; however, an athlete's training status and the dose-response relationship must be considered. While 2- to 5-min interset rest intervals may produce the greatest strength-power benefits, rest interval length may vary based an athlete's training age, fiber type, and genetics. Weaker athletes should focus on developing strength before emphasizing power-type training. Stronger athletes may begin to emphasize power-type training while maintaining/improving their strength. Future research should investigate how best to implement accentuated eccentric loading and variable resistance training and examine how initial strength affects an athlete's ability to improve their performance following various training methods.