Unilateral Exercise Research Articles

Blood flow after exercise-induced muscle damage.

The most common modality used to address acute inflammation is cryotherapy. Whereas pain decreases with cryotherapy, evidence that changes occur in perfusion of skeletal muscle is limited. We do not know whether ice attenuates the increases in perfusion associated with acute inflammation. To examine the effects of repeated applications of ice bags on perfusion of the gastrocnemius muscle after an eccentric exercise protocol. Controlled laboratory study. Laboratory. Eighteen healthy participants (3 men, 15 women; age = 22.2 ± 2.2 years, height = 166.0 ± 11.9 cm, mass = 69.4 ± 25.0 kg). To induce eccentric muscle damage, participants performed 100 unilateral heel-lowering exercises off a step to the beat of a metronome. A randomized intervention (cryotherapy, sham, control) was applied to the exercised lower extremity immediately after the protocol and again at 10, 24, and 34 hours after the protocol. Baseline perfusion measurements (blood volume, blood flow, and blood flow velocity) were taken using contrast-enhanced ultrasound of the exercised leg. Perfusion was reassessed after the first intervention and 48 hours after the protocol as percentage change scores. Pain was measured with a visual analog scale at baseline and at 10, 24, 34, and 48 hours after the protocol. Separate repeated-measures analyses of variance were used to assess each dependent variable. We found no interactions among interventions for microvascular perfusion. Blood volume and blood flow, however, increased in all conditions at 48 hours after exercise (P < .001), and blood flow velocity decreased postintervention from baseline (P = .041). We found a time-by-intervention interaction for pain (P = .009). Visual analog scale scores were lower for the cryotherapy group than for the control group at 34 and 48 hours after exercise. Whereas eccentric muscle damage resulted in increased blood flow, ice did not decrease muscle perfusion 48 hours after exercise. Therefore, ice does not seem to decrease muscle perfusion when blood flow is elevated, as it would be during inflammation.

Progressive Inequality: Rich and Poor in New York, 1890–1920. By David Huyssen (Cambridge, Mass., Harvard University Press, 2014) 378 pp. $39.95

Progressive Inequality is an important, a deeply researched, and an altogether impressive examination of interclass contact and relations in New York City between 1890 and 1920. It is not a new topic; the 1970s saw a cycle of such studies. But this work revises the topic significantly, advancing well beyond the “social control” arguments of that scholarship. Huyssen reveals the elitist disdain at the nexus of the charitable relation, blind and unaware though it be. This cultural history is attentive to language as well as to “robust, often unilateral exercises of power” (16). Huyssen favors a “cooperative” spirit linking the classes, and he is particularly harsh, sometimes even contemptuous, of the language and politics of the leading philanthropists of the 1890s.In the second half of the book, which purports to engage givers who have a better sense of the poor and understand themselves better than their predecessors did, Huyssen makes a category error by eliding Gilded Age reformers and actual Progressives. He misses a generational shift. Those whom he criticizes—Robert W. DeForest, Richard Gilder, and Josephine Shaw Lowell—were all born in the 1840s, whereas the later reformers whom he sees in a more positive light—Lillian Wald, Jane Addams, and Mary Simkovitch—were born in the 1860s; Mary E. Dreier was born in 1875. Hence, the philanthropies of the Gilded Age and the Progressive Era ought to be distinguished, even though his conclusion notes that neither was democratic in a cultural or political sense.Yet generation is not destiny. Regrettably, Huyssen declines to follow Lowell into the Progressive Era, when she began to condemn manufacturers and middle-class consumers for exploiting the poor. The later Lowell was moved by the Haymarket riot, the Homestead strike, and the Henry George campaign for mayor in New York to bring together poor women (“shop girls”) and middle-class women (consumers) in the National Consumer League to collaborate in the name of justice rather than charity: What the “poor want is fair wages and not little doles of food.”1Huyssen admires Wald’s settlement house work, as well as Jacob Schiff’s support of it, adding, however, that Wald’s aid to the poor unavoidably “reflected, rather than subverted, the inequality upon which it rested” (183). The early parts of the book are prosecutorial in tone, whereas the latter chapters are marked by restrained celebration. The alliance of women with money (notably Alva Belmont) and women without money (the seamstresses and various union leaders) become Huyssen’s focus. The great shirtwaist strike of 1909/10 ended inconclusively; a year later, the horrific Triangle Shirtwaist factory fire followed. By that time, interclass mobilization was coming apart.The book ends on that sad note; indeed, the poor, the vulnerable, and the exploited are still with us. Yet the tragedy that paralyzed one generation of New Yorkers mobilized another one—Al Smith, Robert F. Wagner, and Frances Perkins—who brought the state into play in a way that strengthened labor, thus tilting the polity toward more justice, though still not enough.

The effect of modified bridge exercise on balance ability of stroke patients.

[Purpose] The purpose of this study was to verify the effects of a modified bridging exercise on stroke patients with improvement in weight bearing on the affected side in standing and static balancing ability. [Subjects] Thirty patients who had a stroke were randomly allocated into a supine bridge exercise group (SBG, n=10), a supine bridge exercise on a TOGU balance pad group (SBTG, n=10), and a unilateral bridge exercise group (UBG, n=10). [Methods] The SBG patients underwent supine bridge exercise, the SBTG patients underwent supine bridge exercise with a TOGU balance pad, and the UBG patients underwent unilateral bridge exercise. All groups received 20 minutes of training per day, five times per week, for four weeks. [Results] All groups showed significant changes in weight bearing in a standing position after the intervention. The SBTG and UBG groups showed significant changes in balance ability. [Conclusion] According to the results of this study, bridge exercise was effective in improving weight bearing in a standing position and improving balance on stroke patients. The bridge exercise with a TOGU balance pad and the unilateral bridge exercise were especially more effective in anterior, posterior length in limit of stability following on standing.

Unilateral muscle overuse causes bilateral changes in muscle fiber composition and vascular supply.

Unilateral strength training can cause cross-transfer strength effects to the homologous contralateral muscles. However, the impact of the cross-over effects on the muscle tissue is unclear. To test the hypothesis that unilateral muscle overuse causes bilateral alterations in muscle fiber composition and vascular supply, we have used an experimental rabbit model with unilateral unloaded overstrain exercise via electrical muscle stimulation (E/EMS). The soleus (SOL) and gastrocnemius (GA) muscles of both exercised (E) and contralateral non-exercised (NE) legs (n = 24) were morphologically analyzed after 1w, 3w and 6w of EMS. Non-exercised rabbits served as controls (n = 6). After unilateral intervention the muscles of both E and NE legs showed myositis and structural and molecular tissue changes that to various degrees mirrored each other. The fiber area was bilaterally smaller than in controls after 3w of E/EMS in both SOL (E 4420 and NE 4333 µm2 vs. 5183 µm2, p<0.05) and GA (E 3572 and NE 2983 µm2 vs. 4697 µm2, p<0.02) muscles. After 6w of E/EMS, the percentage of slow MyHCI fibers was lower than in controls in the NE legs of SOL (88.1% vs. 98.1%, p<0.009), while the percentage of fast MyHCIIa fibers was higher in the NE legs of GA (25.7% vs. 15.8%, p = 0.02). The number of capillaries around fibers in the E and NE legs was lower (SOL 13% and 15%, respectively, GA 25% and 23%, respectively, p<0.05) than in controls. The overall alterations were more marked in the fast GA muscle than in the slow SOL muscle, which on the other hand showed more histopathological muscle changes. We conclude that unilateral repetitive unloaded overuse exercise via EMS causes myositis and muscle changes in fiber type proportions, fiber area and fiber capillarization not only in the exercised leg, but also in the homologous muscles in the non-exercised leg.

Force irradiation effects during upper limb diagonal exercises on contralateral muscle activation

The aim of this study was to explore the force irradiation effects of upper limb isometric diagonal exercises on shoulder muscle activities. Interactions among diagonal directions, contraction intensities (moderate and maximum) and sex were assessed. Thirty healthy subjects (11 males) performed isometric unilateral diagonal exercises based on proprioceptive neuromuscular facilitation technique in an isokinetic dynamometer with their dominant upper limbs. The second diagonal for flexion and for extension were assessed while the participants performed their maximum isometric torque (MIT) and at 25% of their MIT. During the exercise the muscle activity of the medial deltoid, pectoralis major and upper trapezius in the non-dominant (non-exercised) upper limbs of the participants was recorded by surface electromyography. The highest muscle activity occurred in the upper trapezius during the diagonal for flexion (27% of maximum isometric voluntary contractions). Upper trapezius and pectoralis major were more active during the diagonal for flexion than diagonal for extension (p<0.001), while similar values between both diagonals were observed for the medial deltoid (p>0.05). In conclusion, we observed that force irradiation during upper limb diagonal exercises is affected by diagonal direction, contraction intensity and sex when performed by healthy participants.

Hemodynamic response to resistance exercise with and without blood flow restriction in healthy subjects.

To compare the hemodynamic response during resistance exercise at high intensity (HI), low intensity (LI) and low intensity with blood flow restriction (LI-BFR) in healthy subjects. Twelve men performed three sets of unilateral knee extension exercises at LI-BFR and LI (15 repetitions; 20% of 1RM) and HI (8 repetitions; 80% of 1RM). The blood flow restriction was accomplished using a sphygmomanometer positioned on the thigh and inflated to the point of blood flow interruption (167·9±16·6mmHg). The hemodynamic variables were obtained by continuous beat-to-beat photoplethysmography. Rating of perceived exertion (RPE) and blood lactate were also measured. The HI session showed higher values (P<0·05) in all sets than the LI and LI-BFR for diastolic blood pressure, heart rate and rate-pressure product. The LI-BFR showed higher values than the LI only in the 3rd set for systolic blood pressure, heart rate and rate-pressure product. Blood lactate was higher in the HI (4·2±0·2mmol) and LI-BFR (4·1±0·3mmol) than the LI (3·5±0·3mmol). Rating of perceived exertion was higher in the LI-BFR (7·9±0·3) than the HI (6·4±0·4) and LI (3·2±0·4). The LI-BFR session exhibited similar blood lactate to the HI, a higher rating of perceived response than the HI and LI, and equal or lower hemodynamic responses than the HI.

Upper Limb Exercise Prescription Following Cardiac Surgery via Median Sternotomy

Following cardiac surgery via median sternotomy, patients are routinely advised to adhere to upper limb restrictions to prevent the development of sternal complications. However, there is no definitive evidence to support the clinical application of such restrictions. The purpose of this study was to investigate current physiotherapy practice regarding upper limb exercise guidelines for this population, within outpatient cardiac rehabilitation in Australia. Physiotherapists working within outpatient cardiac rehabilitation programs in Australia were invited to complete a Web survey. The response rate was 77%. The majority of respondents (96%) prescribed upper limb exercises to patients following median sternotomy, with 95% placing restrictions on these exercises. At 6 weeks postoperatively, 58% and 73% of respondents still placed restrictions on unloaded and loaded unilateral upper limb elevation exercises respectively; similarly, 55% and 74% placed restrictions on unloaded and loaded bilateral upper limb elevation exercises, respectively. However, there was a lack of consensus on the type and timing of these restrictions, with patient-reported pain being the main parameter used to guide upper limb exercise prescription and progression. Only 43% reported screening for sternal instability, and if detected, the majority based their management on clinical experience. There is significant variation in practice with respect to the prescription and progression of upper limb exercises, within outpatient cardiac rehabilitation in Australia. Further research is warranted to establish evidence-based guidelines for the upper limb rehabilitation of patients following cardiac surgery via median sternotomy.

Effect of unilateral and bilateral resistance exercise on maximal voluntary strength, total volume of load lifted, and perceptual and metabolic responses.

The present study investigated the effect of unilateral and bilateral resistance exercise (RE) on maximal voluntary strength, total volume of load lifted (TVLL), rating of perceived exertion (RPE) and blood lactate concentration of resistance-trained males. Twelve healthy men were assessed for the leg extension one-repetition maximum (1RM) strength using bilateral and unilateral contractions. Following this assessment, an RE session (3 sets of repetitions to failure) was conducted with bilateral and unilateral (both limbs) contractions using a load of 50% 1RM. The TVLL was calculated by the product of the number of repetitions and the load lifted per repetition. RPE and blood lactate were measured before, during and after each set. Session RPE was measured 30 minutes after RE sessions. There was a significant difference in the bilateral (120.0±11.9) and unilateral (135.0±20.2 kg) 1RM strength (p < 0.05). The TVLL was similar between both RE sessions. Although the repetitions decreased with each successive set, the total number of repetitions completed in the bilateral protocol (48) was superior to the unilateral (40) protocol (p < 0.05). In both bouts, RPE increased with each subsequent set whilst blood lactate increased after set 1 and thereafter remained stable (p < 0.05). The RPE and lactate responses were not significantly different between both sessions. In conclusion, a bilateral deficit in leg extension strength was confirmed, but the TVLL was similar between both RE sessions when exercising to voluntary fatigue. This outcome could be attributed to the number of repetitions completed in the unilateral RE bout. The equal TVLL would also explain the similar perceptual and metabolic responses across each RE session.

Comparison of posture among adolescent male volleyball players and non-athletes.

Due to high training loads and frequently repeated unilateral exercises, several types of sports training can have an impact on the process of posture development in young athletes. The objective of the study was to assess and compare the postures of adolescent male volleyball players and their non-training peers. The study group comprised 104 volleyball players while the control group consisted of 114 non-training individuals aged 14-16 years. Body posture was assessed by the Moiré method. The volleyball players were significantly taller, and had greater body weight and fat-free mass. The analysis of posture relative to symmetry in the frontal and transverse planes did not show any significant differences between the volleyball players and non-athletes. Postural asymmetries were observed in both the volleyball players and the control participants. Lumbar lordosis was significantly less defined in the volleyball players compared to non-training individuals while no difference was observed in thoracic kyphosis. All athletes demonstrated a loss of lumbar lordosis and an increase in thoracic kyphosis. Significant differences in anteroposterior curvature of the spine between the volleyball players and the non-athletes might be associated with both training and body height. Considering the asymmetric spine overloads which frequently occur in sports training, meticulous posture assessment in young athletes seems well justified.

Assessment of functional impairment after knee anterior cruciate ligament reconstruction using cardiorespiratory parameters: a cross-sectional study.

BackgroundA dynamic sub-maximum exercise with the same absolute intensity, performed with different muscle groups, may present exacerbated cardiorespiratory responses. Therefore, cardiorespiratory responses to unilateral exercise may identify bilateral differences. The purpose of this study was to verify whether the cardiorespiratory responses to lower limb exercise display counter-lateral differences, and if they could be used to assist athletes and health professionals involved in rehabilitation.MethodsNine individuals participated in this cross-sectional study. They had been treated in a private rehabilitation clinic and submitted to intra-articular reconstruction of the anterior cruciate ligament. The cycling exercise with the same sub-maximal intensity and with one lower limb was used to gather data. Cardiorespiratory responses to exercise were compared between exercises performed with the involved and uninvolved limb after five minutes of exercise.ResultsCardiorespiratory responses to exercise performed with the involved limb presented higher values after five minutes of cycling: oxygen uptake (+7%), carbon dioxide production (+10%), minute ventilation (+20%), breathing frequency (+19%), ventilatory equivalent for oxygen (+14%), end-tidal pressure of O2 oxygen (+4%), end-tidal pressure of O2 carbon dioxide (-9%) and heart rate (+9%).ConclusionsThe exacerbated responses, including increase of the ventilatory equivalent and decrease of end-tidal pressure of carbon dioxide, indicate that this exercise protocol may be useful in the characterization of the functional deficit of the surgical limb during rehabilitation.

Citrulline does not enhance blood flow, microvascular circulation, or myofibrillar protein synthesis in elderly men at rest or following exercise.

Aging is associated with anabolic resistance, a reduced sensitivity of myofibrillar protein synthesis (MPS) to postprandial hyperaminoacidemia, particularly with low protein doses. Impairments in postprandial skeletal muscle blood flow and/or microvascular perfusion with hyperaminoacidemia and hyperinsulinemia may contribute to anabolic resistance. We examined whether providing citrulline, a precursor for arginine and nitric oxide synthesis, would increase arterial blood flow, skeletal muscle microvascular perfusion, MPS, and signaling through mTORC1. Twenty-one elderly males (65-80 yr) completed acute unilateral resistance exercise prior to being assigned to ingest a high dose (45 g) of whey protein (WHEY) or a low dose (15 g) of whey protein with 10 g of citrulline (WHEY + CIT) or with 10 g of nonessential amino acids (WHEY + NEAA). A primed, continuous infusion of L-[ring-(13)C6] phenylalanine with serial muscle biopsies was used to measure MPS and protein phosphorylation, whereas ultrasound was used to measure microvascular circulation under basal and postprandial conditions in both a rested (FED) and exercised (EX-FED) leg. Argininemia was greater in WHEY + CIT vs. WHEY and WHEY + NEAA from 30 to 300 min postexercise (P < 0.001), but there were no treatment differences in blood flow or microvascular perfusion (all P > 0.05). Phosphorylation of p70S6K-Thr(389) was greater in WHEY vs. WHEY + NEAA (P = 0.02). Postprandial MPS was greater in WHEY vs. WHEY + CIT and WHEY + NEAA under both FED (WHEY: ~128%; WHEY + CIT: ~56%; WHEY + NEAA: ~38%) and EX-FED (WHEY: ~251%; WHEY + CIT: ~124%; WHEY + NEAA: ~108%) conditions (P = 0.003). Citrulline coingestion with a low quantity of protein was ineffective in augmenting the anabolic properties of protein compared with nonessential amino acids.

Effects of unilateral leg muscle fatigue on balance control in perturbed and unperturbed gait in healthy elderly

This study assessed effects of unilateral leg muscle fatigue (ULMF) on balance control in gait during the stance and swing phases of the fatigued leg in healthy elderly, to test the assumption that leg muscle strength limits balance control during the stance-phase.Ten subjects (aged 63.4, SD 5.5 years) walked on a treadmill in 4 conditions: unperturbed unfatigued, unperturbed fatigued, perturbed unfatigued, and perturbed fatigued. The perturbations were lateral trunk pulls just before contralateral heel contact. ULMF was evoked by unilateral squat exercise until task failure. Isometric knee extension strength was measured to verify the presence of muscle fatigue. Between-stride standard deviations and Lyapunov exponents of trunk kinematics were used as indicators of balance control. Required perturbation force and the deviation of trunk kinematics from unperturbed gait were used to assess perturbation responses.Knee extension strength decreased considerably (17.3% SD 8.6%) as a result ULMF. ULMF did not affect steady-state gait balance. Less force was required to perturb subjects when the fatigued leg was in the stance-phase compared to the swing-phase. Subjects showed a faster return to the unperturbed gait pattern in the fatigued than in the unfatigued condition, after perturbations in swing and stance of the fatigued leg.The results of this study are not in line with the hypothesized effects of leg muscle fatigue on balance in gait. The healthy elderly subjects were able to cope with substantial ULMF during steady-state gait and demonstrated faster balance recovery after laterally directed mechanical perturbations in the fatigued than in the unfatigued condition.

Ergospirometric assessment: Relevance for rehabilitation of stroke subjects.

Introduction: Cardiorespiratory fitness is markedly reduced in individuals post stroke, resulting in a pattern of inactivity and sedentary lifestyle. In this sense, tests of aerobic exercise are critical for prescribing this type of training. Aims: To review the available data regarding the cardiorespiratory and metabolic variables, and protocols used to assess cardiorespiratory fitness in individuals post stroke, and discuss their relevance. Method: A literature review in MEDLINE, CINAHL, EMBASE and PEDro database were conducted. The articles identified by the initial search strategy were evaluated according to the following inclusion criteria: (1) had target population including post stroke individuals, (2) used as spirometry instrumentation, (3) reported randomized clinical trials, experimental, or quasi- experimental studies and (4) conducted an analysis of some cardiorespiratory or metabolic parameter to assess cardiorespiratory fitness. Results: Fifteen studies were identified, with a total sample of 665 post stroke individuals. The experimental groups consisted of exercises on cycle ergometer, treadmill, unilateral lower limb exercise on the isokinetic dynamometer, mobility exercises and water exercises. Most studies used the variable oxygen consumption, two analyzed the anaerobic threshold and only one examined the heart rate and respiratory exchange ratio. Conclusion: Although the studies have shown differences among the analyzed variables, and the assessment and training protocols, it was observed evidence that cardiorespiratory variables, mainly oxygen consumption, are sensitive to training.

Effects of 12 weeks of dynamic strength training with local vibration

The purpose of this study was to investigate the chronic effects of dynamic strength training (ST) with local vibration on the maximum strength of elbow flexor muscles. Twenty healthy male untrained volunteers were divided randomly into the following two groups: the conventional training group (CTG) or the vibration training group (VTG). Both groups performed ST for 12 weeks, three times a week. The ST protocol included four sets of 8–10 repetition maximums (RMs) of unilateral elbow flexion exercise. The VTG performed this training protocol with local vibration at a frequency of 30 Hz and amplitude of 6 mm. The mean values of the one repetition maximum (1RM) tests for both groups increased significantly from the pretest week to the fourth week and from the fourth week to the eighth week (CTG: mean 19.02, s = 7.88%, p = 0.01; mean 10.50, s = 6.86%, p = 0.019, respectively; VTG: mean 16.02, s = 8.30%, p = 0.017; mean 12.55, s = 8.76%, p = 0.019, respectively). The increases in the maximal voluntary contraction (MVC) tests were also statistically significant from the pretest week to the fourth week and from the fourth week to the eighth week (CTG: mean 12.32, s = 8.33%, p = 0.004; mean 9.95, s = 5.32%, p = 0.006, respectively; VTG: mean 10.16, s = 11.71%, p = 0.003; mean 10.36, s = 2.96%, p = 0.01, respectively). There was no significant difference between the 1RM and MVC test results in the eighth and twelfth weeks in either group. No significant differences were observed between the groups (p < 0.05). In conclusion, the application of local vibration does not change the chronic effects of dynamic ST in untrained individuals.

Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial

Leucine is a key amino acid involved in the regulation of skeletal muscle protein synthesis. We assessed the effect of the supplementation of a lower-protein mixed macronutrient beverage with varying doses of leucine or a mixture of branched chain amino acids (BCAAs) on myofibrillar protein synthesis (MPS) at rest and after exercise. In a parallel group design, 40 men (21 ± 1 y) completed unilateral knee-extensor resistance exercise before the ingestion of 25 g whey protein (W25) (3.0 g leucine), 6.25 g whey protein (W6) (0.75g leucine), 6.25 g whey protein supplemented with leucine to 3.0 g total leucine (W6+Low-Leu), 6.25 g whey protein supplemented with leucine to 5.0 g total leucine (W6+High-Leu), or 6.25 g whey protein supplemented with leucine, isoleucine, and valine to 5.0 g total leucine. A primed continuous infusion of l-[ring-(13)C6] phenylalanine with serial muscle biopsies was used to measure MPS under baseline fasted and postprandial conditions in both a rested (response to feeding) and exercised (response to combined feeding and resistance exercise) leg. The area under the blood leucine curve was greatest for the W6+High-Leu group compared with the W6 and W6+Low-Leu groups (P < 0.001). In the postprandial period, rates of MPS were increased above baseline over 0-1.5 h in all treatments. Over 1.5-4.5 h, MPS remained increased above baseline after all treatments but was greatest after W25 (∼267%) and W6+High-Leu (∼220%) treatments (P = 0.002). A low-protein (6.25 g) mixed macronutrient beverage can be as effective as a high-protein dose (25 g) at stimulating increased MPS rates when supplemented with a high (5.0 g total leucine) amount of leucine. These results have important implications for formulations of protein beverages designed to enhance muscle anabolism. This trial was registered at clinicaltrials.gov as NCT 1530646.

Postprandial muscle protein synthesis is higher after a high whey protein, leucine-enriched supplement than after a dairy-like product in healthy older people: a randomized controlled trial

BackgroundDecreased ability of muscles to respond to anabolic stimuli is part of the underlying mechanism for muscle loss with aging. Previous studies suggest that substantial amounts of essential amino acids (EAA), whey protein and leucine are beneficial for stimulation of acute muscle protein synthesis in older adults. However, these studies supplied only proteins, and no bolus studies have been done with dairy products or supplements that contained also fat and carbohydrates besides proteins. The aim of this study was to evaluate whether a specifically designed nutritional supplement in older adults stimulates muscle protein synthesis acutely to a greater extent than a conventional dairy product. Moreover, the combined effect with resistance exercise was studied by using a unilateral resistance exercise protocol.MethodsUtilizing a randomized, controlled, double blind study design, healthy older adults received a single bolus of a high whey protein, leucine-enriched supplement (EXP: 20g whey protein, 3g total leucine, 150kcal; n = 9) or an iso-caloric milk protein control (Control: 6g milk protein; n = 10), immediately after unilateral resistance exercise. Postprandial mixed muscle protein fractional synthesis rate (FSR) was measured over 4h using a tracer infusion protocol with L-[ring-13C6]-phenylalanine and regular blood and muscle sampling.ResultsFSR was significantly higher overall after EXP (0.0780 ± 0.0070%/h) vs Control (0.0574 ± 0.0066%/h (EMM ± SE)) (p = 0.049). No interaction between treatment and exercise was observed (p = 0.519). Higher postprandial concentrations of EAA and leucine are possible mediating factors for the FSR response, while plasma insulin increase did not dictate the FSR response. Moreover, when the protein intake from the supplements was expressed per kg leg lean mass (LLM), a significant correlation was observed with resting postprandial FSR (r = 0.48, P = 0.038).ConclusionsIngestion of a high whey protein, leucine-enriched supplement resulted in a larger overall postprandial muscle protein synthesis rate in healthy older subjects compared with a conventional dairy product. This acute effect is promising for long-term effects on parameters of muscle mass, strength and function in sarcopenic older people, which requires further study.Trial registrationThis trial is registered in the Dutch Trial Register under number NTR1823.

EMG Activity in the Abdominal Muscles and the Kinematics of the Lumbar Spine during Unilateral Upper-limb Resistance Exercises under Stable and Unstable Conditions.

[Purpose] We investigated the effects of unstable conditions on the electromyographic (EMG) activity of the rectus abdominis (RA) and the transverse abdominis–internal oblique (TrA-IO) muscles, and lumbar kinematics during unilateral upper-limb resistance exercises using elastic tubing bands. [Subjects] Twelve healthy males were recruited. [Methods] The subjects performed isometric left shoulder abduction using an elastic tubing band in a sitting position on a chair, and on a Swiss ball. During this exercise, EMG activities of the RA and TrA-IO were recorded using a wireless EMG system, and a three-dimensional motion analysis system monitored lumbar kinematics. Differences in EMG activities of the RA and TrA-IO, the ratio of TrA-IO to RA activity, and lumbar kinematics were compared between the stable and unstable conditions using the paired t-test. [Results] Under the unstable condition, the EMG activities of both muscles were significantly greater than that under the stable condition; however the ratio of TrA-IO to RA activity did not significantly differ between the conditions. The lumbar angle significantly differed only in the coronal plane. [Conclusions] These findings indicate that trunk posture should be considered when performing exercises under unstable conditions.

Lower-limb performance disparities: implications for exercise prescription in multiple sclerosis.

The purpose of this study was to examine unilateral lower-limb exercise tolerance during fixed-load cycling to quantify performance disparities of the legs. Eight individuals with relapsing-remitting multiple sclerosis (MS) and seven controls performed submaximal single-leg cycling. Individuals with MS performed significantly more work with the stronger leg than the weaker leg (stronger leg: 6.4 +/- 1.7 kJ, weaker leg: 4.7 +/- 2.5 kJ, p = 0.02). The control group displayed no statistical differences between limbs (p = 0.36). These results highlight a need for individualized exercise testing when prescribing training programs for those with MS.

The effect of repetitive bilateral arm training with rhythmic auditory cueing on motor performance and central motor changes in patients with chronic stroke

The aim of this study was to compare the effects of bilateral arm training with auditory cueing (BATRAC) versus control intervention on motor performance of the upper extremity (UE) and to explore the central neurophysiological mechanism underlying this effect in moderately impaired chronic stroke patients. This was a randomized-controlled clinical trial. Overall, 76 chronic stroke patients (mean age = 50.2 ± 6.2 years), 6–67 months after the onset of the first stroke were enrolled. They received either BATRAC (with both UE trained simultaneously in symmetric and asymmetric patterns) or control intervention (unilateral therapeutic exercises for the paretic UE). Each session lasted for 1 h, scheduled as three sessions/week (on an alternate day) for 8 successive weeks. Outcome measures included the Fugl-Meyer motor performance test for the UE (FMUE) and percutaneous transcranial magnetic stimulation to elicit motor-evoked potential (MEP) in paretic abductor pollicis brevis muscle. Group comparisons indicated a significantly better improvement in the MEP parameters (transcranial magnetic stimulation threshold, central motor conduction time, and MEP amplitude) in the BATRAC group. The FMUE scores increased in both groups, but there was no significant difference between groups in the FMUE scores. These findings recommend the use of BATRAC in chronic stroke patients not only to improve motor performance but also to induce central neurophysiological effects.

The effects of load and effort-matched concentric and eccentric knee extension training in recreational females

PurposeThe purpose of this study was to compare the effects of load and intensity of effort-matched concentric and eccentric knee extension training on isometric strength.MethodsUnilateral isometric torque was measured using a MedX knee extension after which eleven recreationally trained females performed both concentric-only (CONC) and eccentric-only (ECC) unilateral knee extension exercise once per week for 8 weeks. Participants performed a single set of both CONC and ECC exercise loadmatched at 80% of maximum isometric torque for each condition. All participants exercised to repetition maximum in both CONC and ECC conditions at a pace of ~3 s duration for each muscle action. This ensured that participants exercised to the same intensity of effort for both CONC and ECC training interventions.ResultsAnalyses revealed significant increases in isometric torque for both CONC (14.8%) and ECC (13.0%) conditions (&lt;i&gt;p&lt;/i&gt; &lt; 0.05). Absolute change from pre- to post-intervention was compared for CONC and ECC training conditions revealing no statistically significant differences (&lt;i&gt;p&lt;/i&gt; &gt; 0.05). Effect sizes are reported as 0.60 (CONC) and 0.53 (ECC). In addition, analyses revealed significantly greater mean total training volume for ECC compared with CONC conditions (15903 vs. 8091, respectively; &lt;i&gt;p&lt;/i&gt; &lt; 0.001).ConclusionsThe present findings indicate that, when matched for intensity of effort, both CONC and ECC knee extension exercise can significantly improve strength to the same extent. This supports previous research that load and repetitions are not as important as intensity of effort in resistance exercise.