201
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Paschalis V, Nikolaidis MG, Theodorou AA, Giakas G, Jamurtas AZ, Koutedakis Y. Eccentric exercise affects the upper limbs more than the lower limbs in position sense and reaction angle. J Sports Sci 2010; 28:33-43. [PMID: 20013463 DOI: 10.1080/02640410903334764] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
In this study, we investigated the effect of eccentric exercise on position sense and reaction angle of the elbow and knee flexors. Twelve males underwent two eccentric exercise sessions involving a randomized crossover design. In the first session participants used their elbow flexors and in the other session their knee flexors. Muscle damage indices, position sense, and joint reaction angle to release of the elbow and knee flexors were measured before, immediately after, and up to 7 days after exercise. Exercise induced greater muscle damage in the elbow flexors than knee flexors. Exercise disturbed position sense of the elbow and knee joint. For both limbs, the participants adopted a more extended position than the reference angle. The elbow and knee joint reaction angles to release increased after exercise for both the elbow and knee flexors. The disturbances in position sense and reaction angle after exercise were greater in the elbow flexors than knee flexors. The elbow flexors remained more accurate and faster than the knee flexors at all time points. These results may be explained by the higher density of muscle spindles and the lower innervation ratio of the elbow flexors compared with the knee flexors, as well as the fact that the arms are more accustomed than the legs to perform fast and accurate movements.
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Affiliation(s)
- Vassilis Paschalis
- Institute of Human Performance and Rehabilitation, Centre for Research and Technology-Thessaly, Trikala, Greece.
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202
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Easthope CS, Hausswirth C, Louis J, Lepers R, Vercruyssen F, Brisswalter J. Effects of a trail running competition on muscular performance and efficiency in well-trained young and master athletes. Eur J Appl Physiol 2010; 110:1107-16. [PMID: 20703499 DOI: 10.1007/s00421-010-1597-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2010] [Indexed: 10/19/2022]
Abstract
To determine the acute effects of a trail running competition and the age-dependent differences between young and master athletes, 23 subjects [10 young (30.5 ± 7 years), 13 master (45.9 ± 5.9 years)] participated in a 55-km trail running competition. The study was conceived as an intervention study compromising pre, post 1, 24, 48 and 72 h measurements. Measurements consisted of blood tests, ergometer cycling and maximal isometric voluntary contractions (MVC). Parameters monitored included MVC, twitch- and M-wave properties, EMG (RMS) of the vastus lateralis, two locomotion efficiency calculations and muscle damage markers in the blood (CK, LDH). Results indicate post-race increases in CK and LDH, decreases in MVC values (-32 vs. -40% in young and master, P < 0.01), decreases in EMG, increases in contraction time and concomitant decreases in peak twitch values, and a decrease in locomotion efficiency (-4.6 vs. -6.3% in young and master, P < 0.05). Masters showed similar fatigue and muscle damage than young but recuperation was slowed in masters. This study shows that trail runs are detrimental to muscle function, and gives indication that training may not halt muscle deterioration through aging, but can help maintain performance level.
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203
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Lloyd RS, Oliver JL, Hughes MG, Williams CA. Reliability and validity of field-based measures of leg stiffness and reactive strength index in youths. J Sports Sci 2010; 27:1565-73. [PMID: 19967591 DOI: 10.1080/02640410903311572] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The aim of the study was to assess the reliability of a mobile contact mat in measuring a range of stretch-shortening cycle parameters in young adolescents. Additionally, vertical leg stiffness using contact mat data was validated against a criterion method using force-time data. The reliability study involved 18 youths completing a habituation and three separate test sessions, while 20 youths completed a single test session for the validity study. Participants completed three trials of a squat jump, countermovement jump, and maximal hopping test and a single trial of repeated sub-maximal hopping at 2.0 Hz and 2.5 Hz. All tests were performed on the contact mat. Reliability statistics included repeated-measures analysis of variance, intraclass correlation coefficient, and coefficient of variation (CV), while the correlation coefficient (r) and typical error of estimate (TEE) were reported for the validity study. Squat jump height was the most reliable measure (CV = 8.64%), while leg stiffness during sub-maximal hopping, and reactive strength index produced moderate reliability (CV = 10.17-13.93% and 13.98% respectively). Measures of leg stiffness obtained from contact mat data during sub-maximal hopping were in agreement with the criterion measure (r = 0.92-0.95; TEE = 6.5-7.5%), but not during maximal hopping (r = 0.59; TEE = 41.9%). The contact mat was deemed a valid tool for measuring stretch-shortening cycle ability in sub-maximal but not maximal hopping. Although reliability of performance was generally moderate, the tests offer a replicable assessment method for use with paediatric populations.
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Affiliation(s)
- Rhodri S Lloyd
- Cardiff School of Sport, University of Wales Institute Cardiff, Cardiff
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204
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Kinematic analysis of the braking and propulsion phases during the support time in sprint running. Gait Posture 2010; 31:209-12. [PMID: 19926284 DOI: 10.1016/j.gaitpost.2009.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 09/15/2009] [Accepted: 10/16/2009] [Indexed: 02/02/2023]
Abstract
The contact time (CT) and the ratio between the duration of braking (BP) and propulsion phase (PP) during the support are two mechanical parameters that are relevant for the performance in sprinting. Several different kinematic methods have been used to estimate the BP-PP transition point, with some disagreements among studies. The purpose of this study was to compare three criteria to individuate that point: the maximum knee flexion (KNEEFLEX), the maximum fall of the COM (COMVERT) and the horizontal COM acceleration (COMHORIZ). It was hypothesized that these three events would take place in different instants, representing different moments of the step cycle. The kinematic analysis was performed through stereophotogrammetry on seven male middle-level sprinters (mean + or - SD height: 180 + or - 5 cm; body mass: 75 + or - 11 kg; personal best on 100 m: 10.96 + or - 0.45 s). The COMVERT expressed as percentage of CT (mean + or - SD 31.73 + or - 8.29%) was on average strongly anticipated compared to both KNEEFLEX (45.07 + or -3.60%, p < 0.01) and COMHORIZ (56.86 + or - 8.56%, p < 0.01). The approximately 12% difference between KNEEFLEX and COMHORIZ was also statistically significant (p < 0.01). The 40-60% relative proportion of BP and PP considered to be optimal in the literature, was reflected in this study only by the KNEEFLEX criterion. Given the importance of BP time as a reference parameter to assess the training status and efficacy of training interventions, it looks necessary both from a scientific and applied perspective to consider a standardized criterion to identify the BP-PP transition point.
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205
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Bonacci J, Chapman A, Blanch P, Vicenzino B. Neuromuscular adaptations to training, injury and passive interventions: implications for running economy. Sports Med 2010; 39:903-21. [PMID: 19827859 DOI: 10.2165/11317850-000000000-00000] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Performance in endurance sports such as running, cycling and triathlon has long been investigated from a physiological perspective. A strong relationship between running economy and distance running performance is well established in the literature. From this established base, improvements in running economy have traditionally been achieved through endurance training. More recently, research has demonstrated short-term resistance and plyometric training has resulted in enhanced running economy. This improvement in running economy has been hypothesized to be a result of enhanced neuromuscular characteristics such as improved muscle power development and more efficient use of stored elastic energy during running. Changes in indirect measures of neuromuscular control (i.e. stance phase contact times, maximal forward jumps) have been used to support this hypothesis. These results suggest that neuromuscular adaptations in response to training (i.e. neuromuscular learning effects) are an important contributor to enhancements in running economy. However, there is no direct evidence to suggest that these adaptations translate into more efficient muscle recruitment patterns during running. Optimization of training and run performance may be facilitated through direct investigation of muscle recruitment patterns before and after training interventions. There is emerging evidence that demonstrates neuromuscular adaptations during running and cycling vary with training status. Highly trained runners and cyclists display more refined patterns of muscle recruitment than their novice counterparts. In contrast, interference with motor learning and neuromuscular adaptation may occur as a result of ongoing multidiscipline training (e.g. triathlon). In the sport of triathlon, impairments in running economy are frequently observed after cycling. This impairment is related mainly to physiological stress, but an alteration in lower limb muscle coordination during running after cycling has also been observed. Muscle activity during running after cycling has yet to be fully investigated, and to date, the effect of alterations in muscle coordination on running economy is largely unknown. Stretching, which is another mode of training, may induce acute neuromuscular effects but does not appear to alter running economy. There are also factors other than training structure that may influence running economy and neuromuscular adaptations. For example, passive interventions such as shoes and in-shoe orthoses, as well as the presence of musculoskeletal injury, may be considered important modulators of neuromuscular control and run performance. Alterations in muscle activity and running economy have been reported with different shoes and in-shoe orthoses; however, these changes appear to be subject-specific and non-systematic. Musculoskeletal injury has been associated with modifications in lower limb neuromuscular control, which may persist well after an athlete has returned to activity. The influence of changes in neuromuscular control as a result of injury on running economy has yet to be examined thoroughly, and should be considered in future experimental design and training analysis.
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Affiliation(s)
- Jason Bonacci
- Musculoskeletal Pain and Injury Research Unit, University of Queensland, Brisbane, Queensland, Australia
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206
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Cronin NJ, Ishikawa M, Af Klint R, Komi PV, Avela J, Sinkjaer T, Voigt M. Effects of prolonged walking on neural and mechanical components of stretch responses in the human soleus muscle. J Physiol 2009; 587:4339-47. [PMID: 19622608 DOI: 10.1113/jphysiol.2009.174912] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
After repeated passive stretching, tendinous tissue compliance increases in the human soleus (SOL) muscle-tendon unit. During movement, such changes would have important consequences for neural and mechanical stretch responses. This study examined the existence of such effects in response to a 75 min walking intervention. Eleven healthy subjects walked on a treadmill at 4 km h(1) with a robotic stretch device attached to the left leg. Ultrasonography was used to measure SOL fascicle lengths, and surface EMG activity was recorded in the SOL and tibialis anterior (TA) muscles. Perturbations of 6 deg were imposed at three different measurement intervals: Pre (immediately before the walking intervention), Mid (after approximately 30 min of walking) and Post (immediately after the intervention). Between the Pre-Mid and Mid-Post intervals, subjects walked for 30 min at a gradient of 3%. After the intervention, the amplitude and velocity of fascicle stretch both decreased (by 46 and 59%, respectively; P < 0.001) in response to a constant external perturbation, as did short (33%; P < 0.01) and medium (25%; P < 0.01) latency stretch reflex amplitudes. A faster perturbation elicited at the end of the protocol resulted in a recovery of fascicle stretch velocities and short latency reflex amplitudes to the pre-exercise values. These findings suggest that repeated stretching and shortening of a muscle-tendon unit can induce short-term structural changes in the tendinous tissues during human walking. The data also highlight the effect of these changes on neural feedback from muscle sensory afferents.
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Affiliation(s)
- Neil J Cronin
- Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Denmark.
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207
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Abstract
This article describes the physiologic and neural mechanisms that cause neuromuscular fatigue in racquet sports: table tennis, tennis, squash, and badminton. In these intermittent and dual activities, performance may be limited as a match progresses because of a reduced central activation, linked to changes in neurotransmitter concentration or in response to afferent sensory feedback. Alternatively, modulation of spinal loop properties may occur because of changes in metabolic or mechanical properties within the muscle. Finally, increased fatigue manifested by mistimed strokes, lower speed, and altered on-court movements may be caused by ionic disturbances and impairments in excitation-contraction coupling properties. These alterations in neuromuscular function contribute to decrease in racquet sports performance observed under fatigue.
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Affiliation(s)
- Olivier Girard
- EA 2991-Motor Efficiency and Deficiency Lab, Faculty of Sport Sciences, University of Montpellier 1, Montpellier, France.
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208
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Changes in upper body muscle activity with increasing double poling velocities in elite cross-country skiing. Eur J Appl Physiol 2009; 106:353-63. [DOI: 10.1007/s00421-009-1018-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2009] [Indexed: 11/27/2022]
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209
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Duchateau J, Enoka RM. Neural control of shortening and lengthening contractions: influence of task constraints. J Physiol 2008; 586:5853-64. [PMID: 18955381 DOI: 10.1113/jphysiol.2008.160747] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Although the performance capabilities of muscle differ during shortening and lengthening contractions, realization of these differences during functional tasks depends on the characteristics of the activation signal discharged from the spinal cord. Fundamentally, the control strategy must differ during the two anisometric contractions due to the lesser force that each motor unit exerts during a shortening contraction and the greater difficulty associated with decreasing force to match a prescribed trajectory during a lengthening contraction. The activation characteristics of motor units during submaximal contractions depend on the details of the task being performed. Indexes of the strategy encoded in the descending command, such as coactivation of antagonist muscles and motor unit synchronization, indicate differences in cortical output for the two types of anisometric contractions. Furthermore, the augmented feedback from peripheral sensory receptors during lengthening contractions appears to be suppressed by centrally and peripherally mediated presynaptic inhibition of Ia afferents, which may also explain the depression of voluntary activation that occurs during maximal lengthening contractions. Although modulation of the activation during shortening and lengthening contractions involves both supraspinal and spinal mechanisms, the association with differences in performance cannot be determined without more careful attention to the details of the task.
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Affiliation(s)
- Jacques Duchateau
- Laboratory of Applied Biology, Université Libre de Bruxelles, Route de Lennik, 808, CP 640, 1070 Brussels, Belgium.
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210
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211
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Regueme SC, Barthèlemy J, Gauthier GM, Blin O, Nicol C. Delayed influence of stretch-shortening cycle fatigue on large ankle joint position coded with static positional signals. Scand J Med Sci Sports 2008; 18:373-82. [DOI: 10.1111/j.1600-0838.2007.00693.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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212
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Abstract
This article describes the physiologic and neural mechanisms that cause neuromuscular fatigue in racquet sports: table tennis, tennis, squash, and badminton. In these intermittent and dual activities, performance may be limited as a match progresses because of a reduced central activation, linked to changes in neurotransmitter concentration or in response to afferent sensory feedback. Alternatively, modulation of spinal loop properties may occur because of changes in metabolic or mechanical properties within the muscle. Finally, increased fatigue manifested by mistimed strokes, lower speed, and altered on-court movements may be caused by ionic disturbances and impairments in excitation-contraction coupling properties. These alterations in neuromuscular function contribute to decrease in racquet sports performance observed under fatigue.
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213
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Regueme S, Barthèlemy J, Gauthier G, Nicol C. Changes in illusory ankle movements induced by tendon vibrations during the delayed recovery phase of stretch-shortening cycle fatigue: An indirect study of muscle spindle sensitivity modifications. Brain Res 2007; 1185:129-35. [DOI: 10.1016/j.brainres.2007.09.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2007] [Revised: 09/11/2007] [Accepted: 09/12/2007] [Indexed: 10/22/2022]
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214
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Racinais S, Bringard A, Puchaux K, Noakes TD, Perrey S. Modulation in voluntary neural drive in relation to muscle soreness. Eur J Appl Physiol 2007; 102:439-46. [PMID: 17978834 PMCID: PMC2267484 DOI: 10.1007/s00421-007-0604-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/22/2007] [Indexed: 11/10/2022]
Abstract
The aim of this study was to investigate whether (1) spinal modulation would change after non-exhausting eccentric exercise of the plantar flexor muscles that produced muscle soreness and (2) central modulation of the motor command would be linked to the development of muscle soreness. Ten healthy subjects volunteered to perform a single bout of backward downhill walking exercise (duration 30 min, velocity 1 ms−1, negative grade −25%, load 12% of body weight). Neuromuscular test sessions [H-reflex, M-wave, maximal voluntary torque (MVT)] were performed before, immediately after, as well as 1–3 days after the exercise bout. Immediately after exercise there was a −15% decrease in MVT of the plantar flexors partly attributable to an alteration in contractile properties (−23% in electrically evoked mechanical twitch). However, MVT failed to recover before the third day whereas the contractile properties had significantly recovered within the first day. This delayed recovery of MVT was likely related to a decrement in voluntary muscle drive. The decrease in voluntary activation occurred in the absence of any variation in spinal modulation estimated from the H-reflex. Our findings suggest the development of a supraspinal modulation perhaps linked to the presence of muscle soreness.
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Affiliation(s)
- S Racinais
- Motor Efficiency and Deficiency Laboratory, EA 2991, UFR STAPS, Montpellier, France.
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215
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Kivelä R, Kyröläinen H, Selänne H, Komi PV, Kainulainen H, Vihko V. A single bout of exercise with high mechanical loading induces the expression of Cyr61/CCN1 and CTGF/CCN2 in human skeletal muscle. J Appl Physiol (1985) 2007; 103:1395-401. [PMID: 17673559 DOI: 10.1152/japplphysiol.00531.2007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
High mechanical loading was hypothesized to induce the expression of angiogenic and/or lymphangiogenic extracellular matrix (ECM) proteins in skeletal muscle. Eight men performed a strenuous exercise protocol, which consisted of 100 unilateral maximal drop jumps followed by submaximal jumping until exhaustion. Muscle biopsies were taken 30 min and 48 h postexercise from the vastus lateralis muscle and analyzed for the following parameters: mRNA and protein expression of ECM-associated CCN proteins [cysteine-rich angiogenic protein 61 (Cyr61)/CCN1, connective tissue growth factor (CTGF)/CCN2], and mRNA expression of vascular endothelial growth factors (VEGFs) and hypoxia-inducible factor-1α. The mRNA expression of Cyr61 and CTGF increased 30 min after the exercise (14- and 2.5-fold, respectively; P < 0.001). Cyr61 remained elevated 48 h postexercise (threefold; P < 0.05). The mRNA levels of VEGF-A, VEGF-B, VEGF-C, VEGF-D, or hypoxia-inducible factor-1α did not change significantly at either 30 min or 48 h postexercise; however, the variation between subjects increased markedly in VEGF-A and VEGF-B mRNA. Cyr61 protein levels were higher at both 30 min and 48 h after the exercise compared with the control ( P < 0.05). Cyr61 and CTGF proteins were localized to muscle fibers and the surrounding ECM by immunohistochemistry. Fast fibers stained more intensively than slow fibers. In conclusion, mechanical loading induces rapid expression of CCN proteins in human skeletal muscle. This may be one of the early mechanisms involved in skeletal muscle remodeling after exercise, since Cyr61 and CTGF regulate the expression of genes involved in angiogenesis and ECM remodeling.
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Affiliation(s)
- Riikka Kivelä
- LIKES Research Center for Sport and Health Sciences, Rautpohjankatu 8a, FIN-40700 Jyväskylä, Finland.
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216
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Coutts AJ, Slattery KM, Wallace LK. Practical tests for monitoring performance, fatigue and recovery in triathletes. J Sci Med Sport 2007; 10:372-81. [PMID: 17466593 DOI: 10.1016/j.jsams.2007.02.007] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 02/01/2007] [Accepted: 02/02/2007] [Indexed: 11/22/2022]
Abstract
Few studies have described simple tests which can be used to provide an early warning of overreaching. The purpose of this study was to examine selected practical tests for monitoring changes in performance, fatigue and recovery of endurance athletes. Sixteen male triathletes were randomly assigned into matched groups. The normal training (NT) and intensified training (IT) groups completed 4 weeks of training followed by a 2-week taper. Physiological measures were taken pre- and post-overload and post-taper periods during an incremental treadmill test to exhaustion. Performance was assessed weekly using a 3-km run time trial (3 kmTT). Five-bound jump for distance (5BT) and submaximal running heart rate (HR(submax)) test were measured twice weekly and the Daily Analyses of Life Demands for Athletes (DALDA) were recorded. During the overload training period, the IT group completed approximately 290% more training load than the NT group (p<0.001). After the overload training period, 3kmTT in the IT group was reduced compared to both pre-training (3.7%, p<0.05) and the NT group (6.8%, p<0.05). 5BT was decreased by 7.9% in the IT group following the overload period (p<0.05). The IT group also demonstrated increases in stress reaction symptoms from the DALDA. Following the taper, the IT group improved 3 kmTT. In contrast, the performance, physiological and psychological markers of NT group remained relatively unchanged throughout the 6-week training period. There were weak significant correlations between weekly changes in 3 kmTT and 5BT (r=-0.37, p<0.01). The DALDA and 5BT may be practical tests for assessing changes in performance, fatigue and recovery of endurance athletes.
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Affiliation(s)
- Aaron J Coutts
- School of Leisure, Sport and Tourism, University of Technology, Sydney, Australia.
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