Jonathan P. Farthing

Effect of creatine ingestion after exercise on muscle thickness in males and females

UNLABELLED Muscles exercised before creatine (Cr) supplementation have a greater elevation of intramuscular Cr than nonexercised muscles. PURPOSE To determine whether preferential increase of muscle thickness could be achieved by ingesting Cr immediately after exercise of specific muscles over 6 wk. Another purpose was to determine if the increase in lean tissue mass (LTM) with Cr supplementation is greater in males than females. METHODS Subjects randomly assigned to Cr (six males, five females, 0.2 g Cr x kg(-1)) and placebo (PL; five males, five females) performed single-limb training with one side of the body two times per week and with the opposite limbs two times per week. Cr was consumed after training of one side of the body and PL after training the opposite side. Subjects on PL always consumed PL after exercise. Elbow flexors and knee extensors muscle thickness, LTM, fat, and bone mass, and single-limb bench and leg press one-repetition maximum (1-RM) were assessed before and after 6 wk. RESULTS Within the Cr group, elbow flexors muscle thickness increased more in the limbs trained on days Cr was supplemented compared with limbs trained on days PL was supplemented (P < 0.02). All other measures changed to a similar extent between limbs. Males on Cr had the greatest increase in LTM (P < 0.05) with no difference between females on Cr and PL. Bench press 1-RM increased more in Cr than PL groups (P < 0.01). All other measures changed to a similar extent between groups. Males increased bone mass (P < 0.01) with no effect of Cr supplementation. CONCLUSION Supplementing with Cr after training of the arms resulted in greater increase in muscle thickness of the arms. Males have a greater increase in LTM with Cr supplementation than females.

Strength training the free limb attenuates strength loss during unilateral immobilization

The objective was to determine if strength training the free limb during a 3-wk period of unilateral immobilization attenuates strength loss in the immobilized limb through cross-education. Thirty right-handed participants were assigned to three groups. One group (n = 10) wore a cast and trained the free arm (Cast-Train). A second group (n = 10) wore a cast and did not train (Cast). A third group (n = 10) received no treatment (control). Casts were applied to the nondominant (left) wrist and hand by a physician. Strength training was maximal isometric ulnar deviation (right hand) 5 days/wk. Peak torque (dynamometer), electromyography (EMG), and muscle thickness (ultrasound) were assessed in both arms before and after the intervention. Cast-Train improved right arm strength [14.3 (SD 5.0) to 17.7 (SD 4.8) N x m; P < 0.05] with no significant muscle hypertrophy [3.73 (SD 0.43) to 3.84 (SD 0.52) cm; P = 0.09]. The immobilized arm of Cast-Train did not change in strength [13.9 (SD 4.3) to 14.2 (SD 4.6) N x m] or muscle thickness [3.61 (SD 0.51) to 3.57 (SD 0.43) cm]. The immobilized arm of Cast decreased in strength [12.2 (SD 3.8) to 10.4 (SD 2.5) N x m; P < 0.05] and muscle thickness [3.47 (SD 0.59) to 3.32 (SD 0.55) cm; P < 0.05]. Control showed no changes in the right arm [strength: 15.3 (SD 6.1) to 14.3 (SD 5.8) N x m; muscle thickness: 3.57 (SD 0.68) to 3.52 (SD 0.75) cm] or left arm [strength: 14.5 (SD 5.3) to 13.7 (SD 6.1) N x m; muscle thickness: 3.55 (SD 0.77) to 3.51 (SD 0.70) cm]. Agonist muscle activation remained unchanged after the intervention for both arms [right: 302 (SD 188) to 314 (SD 176) microV; left: 261 (SD 139) to 288 (SD 151) microV] with no group differences. Strength training of the free limb attenuated strength loss in the immobilized limb during unilateral immobilization. Strength training may have prevented muscle atrophy in the immobilized limb.

The effects of ibuprofen on muscle hypertrophy, strength, and soreness during resistance training

High doses of ibuprofen have been shown to inhibit muscle protein synthesis after a bout of resistance exercise. We determined the effect of a moderate dose of ibuprofen (400 mg x d(-1)) consumed on a daily basis after resistance training on muscle hypertrophy and strength. Twelve males and 6 females (approximately 24 years of age) trained their right and left biceps on alternate days (6 sets of 4-10 repetitions), 5 d x week(-1), for 6 weeks. In a counter-balanced, double-blind design, they were randomized to receive 400 mg x d(-1) ibuprofen immediately after training their left or right arm, and a placebo after training the opposite arm the following day. Before- and after-training muscle thickness of both biceps was measured using ultrasound and 1 repetition maximum (1 RM) arm curl strength was determined on both arms. Subjects rated their muscle soreness daily. There were time main effects for muscle thickness and strength (p < 0.01). Ibuprofen consumption had no effect on muscle hypertrophy (muscle thickness of biceps for arm receiving ibuprofen: pre 3.63 +/- 0.14, post 3.92 +/- 0.15 cm; and placebo: pre 3.62 +/- 0.15, post 3.90 +/- 0.15 cm) and strength (1 RM of arm receiving ibuprofen: pre 18.6 +/- 2.8, post 23.4 +/- 3.5 kg; and placebo: pre 18.8 +/- 2.8, post 22.8 +/- 3.4 kg). Muscle soreness was elevated during the first week of training only, but was not different between the ibuprofen and placebo arm. We conclude that a moderate dose of ibuprofen ingested after repeated resistance training sessions does not impair muscle hypertrophy or strength and does not affect ratings of muscle soreness.

Effects of cross-education on the muscle after a period of unilateral limb immobilization using a shoulder sling and swathe

The purpose of this study was to apply cross-education during 4 wk of unilateral limb immobilization using a shoulder sling and swathe to investigate the effects on muscle strength, muscle size, and muscle activation. Twenty-five right-handed participants were assigned to one of three groups as follows: the Immob + Train group wore a sling and swathe and strength trained (n = 8), the Immob group wore a sling and swathe and did not strength train (n = 8), and the Control group received no treatment (n = 9). Immobilization was applied to the nondominant (left) arm. Strength training consisted of maximal isometric elbow flexion and extension of the dominant (right) arm 3 days/wk. Torque (dynamometer), muscle thickness (ultrasound), maximal voluntary activation (interpolated twitch), and electromyography (EMG) were measured. The change in right biceps and triceps brachii muscle thickness [7.0 ± 1.9 and 7.1 ± 2.2% (SE), respectively] was greater for Immob + Train than Immob (0.4 ± 1.2 and -1.9 ± 1.7%) and Control (0.8 ± 0.5 and 0.0 ± 1.1%, P < 0.05). Left biceps and triceps brachii muscle thickness for Immob + Train (2.2 ± 0.7 and 3.4 ± 2.1%, respectively) was significantly different from Immob (-2.8 ± 1.1 and -5.2 ± 2.7%, respectively, P < 0.05). Right elbow flexion strength for Immob + Train (18.9 ± 5.5%) was significantly different from Immob (-1.6 ± 4.0%, P < 0.05). Right and left elbow extension strength for Immob + Train (68.1 ± 25.9 and 32.2 ± 9.0%, respectively) was significantly different from the respective limb of Immob (1.3 ± 7.7 and -6.1 ± 7.8%) and Control (4.7 ± 4.7 and -0.2 ± 4.5%, P < 0.05). Immobilization in a sling and swathe decreased strength and muscle size but had no effect on maximal voluntary activation or EMG. The cross-education effect on the immobilized limb was greater after elbow extension training. This study suggests that strength training the nonimmobilized limb benefits the immobilized limb for muscle size and strength.

Changes in Functional Magnetic Resonance Imaging Cortical Activation with Cross Education to an Immobilized Limb

PURPOSE The purpose of this study was to assess cortical activation associated with the cross-education effect to an immobilized limb, using functional magnetic resonance imaging. METHODS Fourteen right-handed participants were assigned to two groups. One group (n = 7) wore a cast and strength trained the free arm (CAST-TRAIN). The second group (n = 7) wore a cast and did not strength train (CAST). Casts were applied to the nondominant (left) wrist and hand. Strength training was maximal isometric handgrip contractions (right hand) 5 d·wk(-1). Peak force (handgrip dynamometer), muscle thickness (ultrasound), EMG, and cortical activation (functional magnetic resonance imaging) were assessed before and after the intervention. RESULTS CAST-TRAIN improved right handgrip strength by 10.7% (P < 0.01) with no change in muscle thickness. There was a significant group × time interaction for strength of the immobilized arm (P < 0.05). Handgrip strength of the immobilized arm of CAST-TRAIN was maintained, whereas the immobilized arm of CAST significantly decreased by 11% (P < 0.05). Muscle thickness of the immobilized arm decreased by an average of 3.3% (P < 0.05) for all participants and was not different between groups after adjusting for baseline differences. There was a significant group × time interaction for EMG activation (P < 0.05), where CAST-TRAIN showed an increasing trend and CAST showed a decreasing trend, pooled across arms. For the immobilized arm of CAST-TRAIN, there was a significant increase in contralateral motor cortex activation after training (P < 0.05). For the immobilized arm of CAST, there was no change in motor cortex activation. CONCLUSIONS Handgrip strength training of the free limb attenuated strength loss during unilateral immobilization. The maintenance of strength in the immobilized limb via the cross-education effect may be associated with increased motor cortex activation.

Greater bilateral deficit in leg press than in handgrip exercise might be linked to differences in postural stability requirements

Bilateral deficit is defined as the difference in the summed force between contracting muscles alone and contracting contralateral homologous muscles in combination. The purpose of the study was to investigate how postural stability influences bilateral deficit by comparing an exercise requiring more postural stability (the leg press) with an exercise requiring less postural stability (the handgrip). Eight participants volunteered for the study (3 males, 5 females). Maximal strength was determined by a 1-repetition maximum for the leg press (weight machine) and handgrip (dynamometer) exercises. Electromyography was used to measure activation of the effectors (flexor carpi ulnaris for the handgrip and vastus lateralis for the leg press) and the core muscles (rectus abdominis and external obliques). Bilateral deficit was greater in the leg press (-12.08 +/- 10.22%) than the handgrip (-0.677 +/- 5.00%; p < 0.05). Muscle activation of the effectors and core muscles was not significantly different between unilateral and bilateral conditions for either exercise. However, core muscle activation was significantly greater during the leg press (48.30 +/- 19.60 microV) than during the handgrip (16.50 +/- 8.10 microV; p < 0.05) exercise. These results support the hypothesis that an exercise requiring more postural stability (e.g., the leg press) will have a larger deficit and greater activation of core muscles than an exercise requiring less postural stability (e.g., the handgrip). Since the bilateral deficit was only apparent for the leg press exercise, we conclude that postural stability requirements might influence the magnitude of bilateral deficit.

Associations between isokinetic muscle strength, high-level functional performance, and physiological parameters in patients with chronic obstructive pulmonary disease

High-level activities are typically not performed by patients with chronic obstructive pulmonary disease (COPD), which results in reduced functional performance; however, the physiological parameters that contribute to this reduced performance are unknown. The aim of this study was to determine the relationships between high-level functional performance, leg muscle strength/power, aerobic power, and anaerobic power. Thirteen patients with COPD underwent an incremental maximal cardiopulmonary exercise test, quadriceps isokinetic dynamometry (isometric peak torque and rate of torque development; concentric isokinetic peak torque at 90°/sec, 180°/sec, and 270°/sec; and eccentric peak torque at 90°/sec), a steep ramp anaerobic test (SRAT) (increments of 25 watts every 10 seconds), and three functional measures (timed up and go [TUG], timed stair climb power [SCPT], and 30-second sit-to-stand test [STS]). TUG time correlated strongly (P < 0.05) with all muscle strength variables and with the SRAT. Isometric peak torque was the strongest determinant of TUG time (r = −0.92). SCPT and STS each correlated with all muscle strength variables except concentric at 270°/sec and with the SRAT. The SRAT was the strongest determinant of SCPT (r = 0.91), and eccentric peak torque at 90°/sec was most significantly associated with STS (r = 0.81). Performance on the SRAT (anaerobic power); slower-velocity concentric, eccentric, and isometric contractions; and rate of torque development are reflected in all functional tests, whereas cardiopulmonary exercise test performance (aerobic power) was not associated with any of the functional or muscle tests. High-level functional performance in patients with COPD is associated with physiological parameters that require high levels of muscle force and anaerobic work rates.

Role of the Mirror-Neuron System in Cross-Education

The present review proposes the untested hypothesis that cross-education performed with a mirror increases the transfer of motor function to the resting limb compared with standard cross-education interventions without a mirror. The hypothesis is based on neuroanatomical evidence suggesting an overlap in activated brain areas when a unilateral motor task is performed with and without a mirror in the context of cross-education of the upper extremities. The review shows that the mirror-neuron system (MNS), connecting sensory neurons responding to visual properties of an observed action and motor neurons that discharge action potentials during the execution of a similar action, has the potential to enhance cross-education. After a literature search we narrowed the review to studies that examined healthy young adults who performed unilateral strength training and unilateral motor tasks with or without a mirror and assessed outcome measures in relation to the changes in brain activity, motor cortical excitability, and corticospinal excitability. We identified six chronic studies that examined the effects of unilateral strength training on neural adaptations and 15 cross-sectional studies that examined acute changes in brain activation, motor cortical and corticospinal excitability using imaging, electroencephalographic, magnetoencephalographic, and magnetic brain stimulation. There were two chronic and nine cross-sectional studies in which participants performed unilateral motor tasks while viewing the image of the active hand superimposed on the resting hand’s image. Collectively, the data suggest that the MNS is involved in cross-education and the hypothesis is tenable. However, future studies are needed to elucidate the precise mechanism of how the use of a mirror in a cross-education study augments transfer to the non-exercised limb. Recent studies show a strength-sparing effect in the immobilized arm after strength training of the free arm in healthy individuals, and improved bilateral function after unilateral exercise therapy in stroke patients. It is thus conceptually justified to conduct randomized clinical trials that supplement cross-education protocols with a mirror. Such a treatment could reduce muscle weakness caused by limb fractures, anterior-cruciate ligament reconstruction surgery, stroke, and other unilateral motor dysfunctions.

Mirror training to augment cross-education during resistance training: a hypothesis

Resistance exercise has been shown to be a potent stimulus for neuromuscular adaptations. These adaptations are not confined to the exercising muscle and have been consistently shown to produce increases in strength and neural activity in the contralateral, homologous resting muscle; a phenomenon known as cross-education. This observation has important clinical applications for those with unilateral dysfunction given that cross-education increases strength and attenuates atrophy in immobilized limbs. Previous evidence has shown that these improvements in the transfer of strength are likely to reside in areas of the brain, some of which are common to the mirror neuron system (MNS). Here we examine the evidence for the, as yet, untested hypothesis that cross-education might benefit from observing our own motor action in a mirror during unimanual resistance training, thereby activating the MNS. The hypothesis is based on neuroanatomical evidence suggesting brain areas relating to the MNS are activated when a unilateral motor task is performed with a mirror. This theory is timely because of the growing body of evidence relating to the efficacy of cross-education. Hence, we consider the clinical applications of mirror training as an adjuvant intervention to cross-education in order to engage the MNS, which could further improve strength and reduce atrophy in dysfunctional limbs during rehabilitation.

Community-dwelling female fallers have lower muscle density in their lower legs than non-fallers: evidence from the Saskatoon Canadian Multicentre Osteoporosis Study (CaMos) cohort

ObjectiveOur objectives were to determine whether peripheral quantitative computed tomography (pQCT)-derived lower leg muscle density and area, and basic functional mobility differ between communitydwelling older women who do and do not report recent falls.DesignMatched case-control comparison.SettingAcademic biomedical imaging laboratory.Participants147 Women, 60 years or older (mean age 74.3 y, SD 7.7) recruited from a longitudinal, population-based cohort representing community-dwelling residents in the area of Saskatoon, Canada.MeasurementsA cross-sectional pQCT scan of the non-dominant lower leg was acquired to determine muscle density and area. Basic functional mobility (Timed Up and Go Test [TUG]) and SF36 health status were also measured. Fallers (one or more falls) and non-fallers (no falls) were grouped according to a 12-month retrospective survey and matched on measured covariates.ResultsThe muscle density of fallers (n = 35) was a median of 2.1 mg/cm3 lower (P = 0.019, 95% C.I. −3.9 to −0.1) than non-fallers (n = 78) after matching and adjusting for age, body mass index, and SF36 general health scores. Muscle area and TUG did not differ between fallers and non-fallers.ConclusionMuscle density may serve as a physiological marker in the assessment of lower leg muscular health and fall risk in community-dwelling elderly women. These results are limited to our study population who were mostly Caucasian. Prospective studies are required for verification.