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1.
Eur J Appl Physiol ; 124(5): 1609-1620, 2024 May.
Article in English | MEDLINE | ID: mdl-38175273

ABSTRACT

PURPOSE: This study aimed to investigate physiological responses, muscle-tendon unit properties of the quadriceps muscle, and mechanical performance after repeated sprint cycling at optimal and 70% of optimal cadence. METHODS: Twenty recreational cyclists performed as first sprint performance cycling test and during subsequent sessions two repeated sprint cycling protocols at optimal and 70% of optimal cadence, in random order. The muscle-tendon unit outcome measures on the dominant leg included muscle thickness, fascicle length (Lf), pennation angle (θp), and stiffness for the rectus femoris (RF), vastus lateralis (VL), and vastus medialis muscle (VM) at baseline, immediately after repeated sprint cycling, and 1-h post-exercise. RESULTS: The results showed an increase in muscle thickness and θp in RF, VL, and VM for both cadences from baseline to immediately after exercise. The Lf decreased in RF (both cadences), while stiffness decreased in RF, VL, and VM at optimal cadence, and in VL at 70% of optimal cadence from baseline to immediately after exercise. CONCLUSION: The present study revealed that the alterations in muscle characteristics were more marked after repeated sprint cycling at optimal cadence compared with a lower cadence most likely as a result of higher load on the muscle-tendon unit at optimal cadence.


Subject(s)
Bicycling , Humans , Male , Bicycling/physiology , Adult , Muscle, Skeletal/physiology , Quadriceps Muscle/physiology , Quadriceps Muscle/diagnostic imaging , Athletic Performance/physiology , Muscle Contraction/physiology , Young Adult
2.
Int J Exerc Sci ; 15(1): 1142-1155, 2022.
Article in English | MEDLINE | ID: mdl-35989701

ABSTRACT

It was investigated whether the phenomenon of repeated bout rate enhancement occurs during submaximal ergometer cycling. Repeated bout rate enhancement is defined as an increase of the freely, or spontaneously, chosen cadence during repeated bouts of pedalling and has previously been reported for finger tapping. This is relevant to study since cadence can affect biomechanical and physiological responses. Recreationally active individuals (n=27) performed five consecutive 5-min bouts of cycling at 100 W using freely chosen cadence. All bouts were separated by 10-min rest. Cadence, pedal force profile characteristics, heart rate, tympanic temperature, and rate of perceived exertion were determined during cycling. The primary result was that cadence at the end of 5. bout was statistically significantly higher than at the end of all other bouts. Overall, the cadence at the end of 5. bout was 15.6%±20.4% higher than at the end of 1. bout. The altered rhythmic motor behaviour was accompanied by a statistically significant effect of bout on the pedal force profile. Also, there was a statistically significant effect of bout on heart rate, which amounted to 125±17 and 131±26 beats/min at the end of 1. and 5. bout, respectively. Perhaps the observed increase of cadence occurred as a nonconscious rhythmogenesis process in form of a net excitation of relevant parts of the nervous system. In conclusion, repeated bout rate enhancement during submaximal ergometer cycling occurred. The freely chosen cadence showed an increase of on average about 15%, or 10 rpm, as accumulated values across five bouts of cycling.

3.
Biol Sport ; 39(2): 289-293, 2022 Mar.
Article in English | MEDLINE | ID: mdl-35309522

ABSTRACT

Moderate paddling, as in long distance kayaking, constitutes an endurance activity, which shares energetic aspects with activities such as long distance running and road cycling. The aim of the present study was to investigate whether in moderate paddling there is a U-shaped relationship between oxygen uptake and stroke rate, and also whether elite kayakers apply a freely chosen stroke rate, which is energetically optimal. Eleven young male elite kayakers performed moderate kayak ergometry at preset target stroke rates of 65, 75, and 90 strokes min-1, and at a freely chosen stroke rate, while physiological responses including oxygen uptake were measured. The results showed that considering average values calculated across all participants, there was an approximately U-shaped relationship between oxygen uptake and target stroke rate with a minimum at 75 strokes min-1. The freely chosen stroke rate was 67.0 ± 6.1 strokes min-1. Thus, the freely chosen stroke rate, for the group in total, appeared to be lower and require higher oxygen uptake as compared to the energetically optimal preset target stroke rate. Eight out of 11 participants had a higher oxygen uptake (5.1% ± 6.7%, p = 0.028, across all participants) at their freely chosen stroke rate than at the preset target stroke rate, which resulted in the lowest oxygen uptake. In conclusion, an approximately U-shaped relationship between oxygen uptake and stroke rate for young elite kayakers during moderate ergometer kayaking was found. Additionally, the freely chosen stroke rate was systematically lower and, consequently, required higher oxygen uptake than the preset stroke rate, which resulted in the lowest oxygen uptake.

4.
Front Sports Act Living ; 4: 1027787, 2022.
Article in English | MEDLINE | ID: mdl-36704264

ABSTRACT

Introduction: Cycling is a time-consuming sport. Cyclists, as many other athletes, therefore, focus on training effectively. The hypothesis was tested that twelve weeks of supplementary maximal acceleration training caused more favourable changes in cycling performance indicators as compared to changes measured in comparable control cyclists. Methods: Trained cyclists (n = 24) participated. A control group and a group performing maximal acceleration training, as a supplement to their usual training, were formed. The maximal acceleration training consisted of series of ten repetitions of outdoor brief maximal accelerations, which were initiated from low speed and performed in a large gear ratio. The cyclists in the control group performed their usual training. Performance indicators, in form of peak power output in a 7-s maximal isokinetic sprint test, maximal aerobic power output in a graded test, and submaximal power output at a predetermined blood lactate concentration of 2.5 mmol L-1 in a graded test were measured before and after the intervention. Results: Peak power output in the sprint test was increased (4.1% from before to after the intervention) to a larger extent (p = 0.045) in the cyclists who had performed the maximal acceleration training than in the control cyclists (-2.8%). Changes in maximal aerobic power output and in submaximal power output at a blood lactate concentration of 2.5 mmol L-1 were not significantly different between the groups (p > 0.351). Discussion: The results indicated that the applied supplementary maximal acceleration training caused modest favourable changes of performance indicators, as compared to the changes measured in a group of comparable control cyclists.

5.
Eur J Appl Physiol ; 121(11): 3041-3049, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34286367

ABSTRACT

PURPOSE: History dependence can refer to the fact that parts of the human physiology (e.g., one or a group of muscles, or the nervous system) as well as functional aspects of the human (e.g., motor behaviour, or performance) depend on prior muscle activation. In the present study, it was investigated whether initial cycling at relatively low and high preset target cadences affected a subsequent freely chosen cadence at the end of the same bout of submaximal ergometer cycling. METHODS: Twenty-two participants performed a single test session, which consisted of separate bouts of submaximal ergometer cycling. In one bout, cycling at 50 rpm was followed by cycling at freely chosen cadence. In another bout, cycling at 90 rpm was followed by cycling at freely chosen cadence. In yet another bout (denoted reference), the cadence was freely chosen throughout. Behavioural (cadence), biomechanical (tangential pedal force), and physiological (heart rate) responses were measured. RESULTS: Increased cadence resulted in decreased maximal tangential pedal force in accordance with existing knowledge. Initial cycling at 50 and 90 rpm caused freely chosen cadence to be about 5% lower and higher, respectively, than the freely chosen cadence (72.4 ± 2.4 rpm) at the end of the reference bout. These differences in cadence were not accompanied by statistically significant differences in heart rate. CONCLUSION: The freely chosen cadence depended on the preset cadence applied at the beginning of the bout. This was denoted a phenomenon of motor behavioural history dependence.


Subject(s)
Bicycling/physiology , Physical Exertion/physiology , Biomechanical Phenomena , Ergometry , Exercise Test , Female , Humans , Male , Oxygen Consumption/physiology , Young Adult
6.
Gait Posture ; 86: 319-326, 2021 05.
Article in English | MEDLINE | ID: mdl-33839426

ABSTRACT

BACKGROUND: The walk-to-run transition, which occurs during gradually increasing locomotion speed, has been addressed in research at least eight decades back. RESEARCH QUESTION: Why does the walk-to-run transition occur? In the present review, we focus on the reason for the transition, more than on the consequences of it. The latter has historically constituted a primary focus. METHODS: In the present review, we scrutinize related literature. RESULTS: We present a unifying conceptual framework of the dynamics of human locomotion. The framework unifies observations of the human walk-to-run transition for providing a common understanding. Further, the framework includes a schematic representation of the dynamic interaction between entities of subsystems of the human body during locomotion and the physical environment. We propose that the moving human body can behave as a dynamic non-linear complex system, which basically functions in a self-organized fashion during locomotion. Further, that the stride rate plays a particular key role for the transition. Finally, we propose that the coincidence between attractor stability and minimum energy turnover during locomotion is a consequence of the evolution of the phenotype of the adult human body and the dynamics of the acute process of self-organization during locomotion. SIGNIFICANCE: The novel insight from the present work contributes to the academic understanding of human locomotion, including in particular the central behavioural phenomenon of walk-to-run transition. Furthermore, the understanding is relevant for the ongoing work within for example locomotion rehabilitation and development of assistive devices. Regarding the latter, examples could be devices within neurorobotics and exoskeletons where the basic understanding of human locomotion increases the possibility of a successful combination of human and technology.


Subject(s)
Running/physiology , Walking/physiology , Adult , Biomechanical Phenomena , Female , Humans , Male
7.
Ergonomics ; 64(5): 571-581, 2021 May.
Article in English | MEDLINE | ID: mdl-33210555

ABSTRACT

This randomised controlled field study aimed to design a female-specific cycling pad with reduced padding in the crotch area (half-pad) and test its effects on self-reported sensory manifestations in comparison with full-padded cycling bib shorts. Recreational female road cyclists (n = 183) participated (divided into two groups). Self-reported sensory manifestations were collected six times over 12 weeks. Sitting discomfort, wetness perception, thermal, texture sensation, and wear discomfort decreased over time for the crotch and sitting-bones areas in both groups. Irritation and tenderness in the crotch area also decreased over time in both groups. Irritation and tenderness in the sitting-bones area were only higher at week two in the half-pad compared with the full-pad group. Cycling with the half-padded shorts compared with the full-padded ones had no negative effects on sensory manifestations beside the observed transient change at week two. This suggests that foam thickness in the crotch area can be reduced in female-specific cycling pads. Practitioner's Summary: Road cycling might result in discomfort and non-traumatic injuries in the female genital area. This field study compares two different cycling pads; a half-pad and a full-pad, over a 12-week period among female recreational road cyclists. Reducing the foam thickness in the crotch area of the pad does not change sensory manifestations, i.e. discomfort, wetness perception, texture-, and thermal-sensation as well as wear discomfort. Abbreviations: CS-Q: online Cycling bib Shorts Questionnaire; VADER: Valence Aware Dictionary and sEntiment Reasoner.


Subject(s)
Bicycling , Female , Humans , Self Report , Surveys and Questionnaires
8.
J Mot Behav ; 52(1): 89-96, 2020.
Article in English | MEDLINE | ID: mdl-30924400

ABSTRACT

These hypotheses were tested: (1) Freely chosen frequency in unilateral index finger tapping is correlated between the two index fingers, and (2) A 3-min bout of unilateral index finger tapping followed by 10 min rest results in an increase of the freely chosen tapping frequency performed by the contralateral index finger in a second bout. Thirty-two adults participated. Freely chosen tapping frequencies from first bouts were 167.2 ± 79.0 and 161.5 ± 69.4 taps/min for the dominant and non-dominant hand, respectively (p=.434). These variables correlated (R=.86, p<.001). When bout one and two were performed with the dominant and non-dominant hand, respectively, the frequency increased by 8.1%±17.2% in bout two (p=.011). In opposite order, the frequency increased by 14.1%±17.5% (p<.001), which was not different from the ∼8% (p=.157).


Subject(s)
Fingers/physiology , Functional Laterality/physiology , Adult , Female , Humans , Male , Time Factors , Young Adult
9.
Front Neurosci ; 12: 526, 2018.
Article in English | MEDLINE | ID: mdl-30108479

ABSTRACT

Voluntary rhythmic movements, such as, for example, locomotion and other cyclic tasks, are fundamental during everyday life. Patients with impaired neural or motor function often take part in rehabilitation programs, which include rhythmic movements. Therefore, it is imperative to have the best possible understanding of control and behaviour of human voluntary rhythmic movements. A behavioural phenomenon termed repeated bout rate enhancement has been established as an increase of the freely chosen index finger tapping frequency during the second of two consecutive tapping bouts. The present study investigated whether the phenomenon would be elicited when the first bout consisted of imposed passive finger tapping or air tapping. These two forms of tapping were applied since they can be performed without descending drive (passive tapping) and without afferent feedback related to impact (air tapping) - as compared to tapping on a surface. Healthy individuals (n = 33) performed 3-min tapping bouts separated by 10 min rest. Surface electromyographic, kinetic, and kinematic data were recorded. Supportive experiments were made to measure, for example, the cortical sensory evoked potential (SEP) response during the three different forms of tapping. Results showed that tapping frequencies in the second of two consecutive bouts increased by 12.9 ± 14.8% (p < 0.001), 9.9 ± 6.0% (p = 0.001), and 16.8 ± 13.6% (p = 0.005) when the first bout had consisted of tapping, passive tapping, and air tapping, respectively. Rate enhancement occurred without increase in muscle activation. Besides, the rate enhancements occurred despite that tapping, as compared with passive tapping and air tapping, resulted in different cortical SEP responses. Based on the present findings, it can be suggested that sensory feedback in an initial bout increases the excitability of the spinal central pattern generators involved in finger tapping. This can eventually explain the phenomenon of repeated bout rate enhancement seen after a consecutive bout of finger tapping.

10.
Int J Exerc Sci ; 11(1): 776-784, 2018.
Article in English | MEDLINE | ID: mdl-29997726

ABSTRACT

A priority in strength and power exercise might be to train with as high quality as possible for the shortest possible duration. In this context, peak power output could reflect quality. Designing an exercise session as a cluster set structure, as compared to a traditional set structure, may be a way to obtain higher peak power output in the session. But it is unknown whether that is obtainable for non-elite individuals performing loaded jump squat exercise. The aim of the present study was therefore to test the hypothesis that peak power output would be highest in a jump squat exercise session, which was structured with cluster sets, as compared to traditional sets. Ten individuals (2 women, 8 men; 26.5 ± 4.8 years, 1.81 ± 0.08 m, 90.9 ± 13.2 kg) performed two loaded jump squat exercise sessions structured with cluster sets and traditional sets, respectively. The sessions were performed on two separate days, in counterbalanced order. The position of the barbell was used to calculate derived values including peak power output. Values calculated as averages across the entire exercise sessions showed peak power output to be 178 ± 181 W, corresponding to 4.1% ± 4.9%, higher in the session with cluster set structure, as compared to the session with traditional set structure (p = 0.005). It was concluded that for non-elite individuals, peak power output was approximately 4% higher in a loaded jump squat exercise session structured with cluster sets as compared to an exercise session structured with traditional sets.

11.
Appl Ergon ; 70: 175-181, 2018 Jul.
Article in English | MEDLINE | ID: mdl-29866308

ABSTRACT

The objectives were 1) to design and produce two novel unpadded bicycle saddles with a wide/medium width and partial nose cutout; 2) to investigate the responses on pressure distribution and perceived discomfort in female cyclists. For comparison, a standard saddle was also tested. Nineteen female cyclists pedaled on an ergometer cycle for 20 min with each saddle in a counterbalanced order. A pressure mat measured saddle interface pressure. Discomfort ratings were collected using a visual analogue scale. Total mean saddle pressure remained similar across saddles. The wide saddle increased anterior and decreased posterior mean saddle pressure as compared with the standard (p < .002) and the medium saddle (p < .001). Significantly increased ischial tuberosity discomfort was found for the novel saddles (p < .001), while crotch discomfort was not significantly different between saddles. The medium width saddle appeared to be the best compromise since increased crotch discomfort was avoided and saddle pressures were redistributed. Such design may be suggested as an alternative to traditional saddles for women reporting discomfort in the perineal region.


Subject(s)
Bicycling , Equipment Design , Pain/etiology , Pressure/adverse effects , Adult , Bicycling/injuries , Buttocks , Ergometry/instrumentation , Ergonomics , Female , Humans , Ischium/anatomy & histology , Perineum , Transducers, Pressure , Young Adult
12.
Int J Sports Physiol Perform ; 12(9): 1127-1136, 2017 Oct.
Article in English | MEDLINE | ID: mdl-28095074

ABSTRACT

The present article reviews effects of training at low imposed cadences in cycling. The authors performed a systematic literature search of MEDLINE and SPORTDiscus up to April 2016 to identify potentially relevant articles. Based on the titles and abstracts of the identified articles, a subset of articles was selected for evaluation. These articles constituted original-research articles on adaptation to training at different imposed cadences in cycling. Seven articles were selected for evaluation. With regard to the terminology in the present article, low cadences are those below the freely chosen cadence. The rate of 80 rpm can, eg, be considered a low cadence if effort is maximal. On the other hand, the cadence has to be lower than 80 rpm (eg, 40-70 rpm) to be considered low if cycling is performed at low power output. The reason is that the choice of cadence depends on power output. In conclusion, there is presently no strong evidence for a benefit of training at low cadences. It can tentatively be recommended to consider including training bouts of cycling at low cadence at moderate to maximal intensity. The reason for the restrained recommendation is that some of the selected studies indicate no clear performance-enhancing effect of training at low cadence or even indicate a superior effect from training at freely chosen cadence. Furthermore, the selected studies are considerably dissimilar with respect to, eg, participant characteristics and to the applied training regimens.


Subject(s)
Adaptation, Physiological , Bicycling/physiology , Physical Conditioning, Human/methods , Physical Exertion , Humans
13.
J Electromyogr Kinesiol ; 27: 78-86, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26938676

ABSTRACT

The aim of this study was to measure and analyse discomfort and biomechanics of cycling, i.e., muscle activation, centre of pressure of seat pressure profiles and pedal forces as a function of seat position. Twenty-one recreationally active individuals cycled for 10min at 100W on an ergometer cycle using five different seat positions. The neutral position was considered as basic seat position and was compared with upward, downward, forward and backward seat positions. The initial bout was repeated at the end of the recording session. Discomfort increased for upward and backward condition compared with neutral (P<0.05). Normalized surface electromyography from gastrocnemius decreased in the downward and forward position but increased in the upward and backward position. The minimum force became less negative for forward position compared with neutral seat position (P<0.05). The degree of variability of centre of pressure increased in the upward and backward position and the entropy of the centre of pressure of sitting posture for backward position decreased compared with neutral seat position (P<0.05). The present study revealed that consecutive changes of seat position over time lead to increase in discomfort as well as alterations of the biomechanics of cycling.


Subject(s)
Bicycling/physiology , Exercise Test/methods , Muscle, Skeletal/physiology , Posture/physiology , Pressure , Adult , Biomechanical Phenomena/physiology , Electromyography/methods , Female , Foot/physiology , Humans , Male , Single-Blind Method , Young Adult
14.
J Strength Cond Res ; 30(7): 1948-59, 2016 Jul.
Article in English | MEDLINE | ID: mdl-26645673

ABSTRACT

Kristiansen, M, Samani, A, Madeleine, P, and Hansen, EA. Effects of 5 weeks of bench press training on muscle synergies: A randomized controlled study. J Strength Cond Res 30(7): 1948-1959, 2016-The ability to perform forceful muscle contractions has important implications in sports performance and in activities of daily living. However, there is a lack of knowledge on adaptations in intermuscular coordination after strength training. The purpose of this study was therefore to assess muscle synergies before and after 5 weeks of bench press training. Thirty untrained male subjects were randomly allocated to a training group (TRA) or a control group (CON). After the pretest, TRA completed 5 weeks of bench press training, before completing a posttest, whereas subjects in CON continued their normal life. During test sessions, surface electromyography (EMG) was recorded from 13 different muscles. Muscle synergies were extracted from EMG data using nonnegative matrix factorization. To evaluate differences between pretest and posttest, we performed a cross-correlation analysis and a cross-validation analysis, in which the synergy components extracted in the pretest session were recomputed, using the fixed synergy components from the posttest session. Two muscle synergies accounted for 90% of the total variance and reflected the concentric and eccentric phase, respectively. TRA significantly increased 3 repetition maximum in bench press with 19.0% (25th; 75th percentile, 10.3%; 21.7%) (p < 0.001), whereas no change occurred in CON. No significant differences were observed in synergy components between groups. However, decreases in correlation values for intragroup comparisons in TRA may suggest that the synergy components changed, whereas this was not the case in CON. Strength and conditioning professionals may consider monitoring changes in muscle synergies in training and rehabilitation programs as a way to benchmark changes in intermuscular coordination.


Subject(s)
Adaptation, Physiological , Muscle Strength , Muscle, Skeletal/physiology , Resistance Training , Adult , Electromyography , Humans , Male , Muscle Contraction , Young Adult
15.
Gait Posture ; 42(1): 60-4, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25943407

ABSTRACT

Despite biomechanical differences between walking, running, and cycling, these types of movement are supposedly generated by shared neural networks. According to this hypothesis, we investigated relationships between movement frequencies in these tasks as well as effects of strength training on locomotion behaviour. The movement frequencies during walking, running, and cycling were 58.1±2.6 strides min(-1), 81.3±4.4 strides min(-1), and 77.2±11.5 revolutions min(-1), respectively (n=27). Stride frequencies in walking and running correlated positively (r=0.72, p<0.001) while no significant correlations were found between stride frequencies during walking and running, respectively, and pedalling frequency (r=0.16, p=0.219 and r=0.04, p=0.424). Potential changes in the freely chosen stride frequencies and stride phase characteristics were also investigated during walking and running through 4 weeks of (i) hip extension strength training (n=9), (ii) hip flexion strength training (n=9), and (iii) no intervention (n=9). Results showed that stride characteristics were unaffected by strength training. That is in contrast to previous observations of decreased pedalling frequency following strength training. In total, these results are proposed to indicate that walking and running movements are robustly generated due to an evolutionary consolidation of the interaction between the musculoskeletal system and neural networks. Further, based on the present results, and the fact that cycling is a postnatally developed task that likely results in a different pattern of descending and afferent input to rhythm generating neural networks than walking and running, we propose pedalling to be generated by neural networks mainly consolidated for locomotion.


Subject(s)
Bicycling/physiology , Gait/physiology , Locomotion/physiology , Resistance Training , Running/physiology , Walking/physiology , Adult , Female , Humans , Male , Nerve Net/physiology , Statistics as Topic , Young Adult
16.
Muscle Nerve ; 52(6): 1066-71, 2015 Dec.
Article in English | MEDLINE | ID: mdl-25762463

ABSTRACT

INTRODUCTION: The aim of this study was to investigate the between-day reliability of the trapezius muscle H-reflex and M-wave. METHODS: Sixteen healthy subjects were studied on 2 consecutive days. Trapezius muscle H-reflexes were evoked by electrical stimulation of the C3/4 cervical nerves; M-waves were evoked by electrical stimulation of the accessory nerve. Relative reliability was estimated by intraclass correlation coefficients (ICC2,1 ). Absolute reliability was estimated by computing the standard error of measurement (SEM) and the smallest real difference (SRD). Bland-Altman plots were constructed to detect any systematic bias. RESULTS: Variables showed substantial to excellent relative reliability (ICC = 0.70-0.99). The relative SEM ranged from 1.4% to 34.8%; relative SRD ranged from 3.8% to 96.5%. No systematic bias was present in the data. CONCLUSIONS: The amplitude and latency of the trapezius muscle H-reflex and M-wave in healthy young subjects can be measured reliably across days.


Subject(s)
Evoked Potentials, Motor/physiology , H-Reflex/physiology , Muscle Contraction/physiology , Superficial Back Muscles/physiology , Adult , Analysis of Variance , Electric Stimulation , Electromyography , Female , Humans , Male , Reaction Time/physiology , Reproducibility of Results , Young Adult
17.
Med Eng Phys ; 36(12): 1656-64, 2014 Dec.
Article in English | MEDLINE | ID: mdl-25277830

ABSTRACT

In this study, we applied multi-channel mechanomyographic (MMG) recordings in combination with linear and nonlinear analyses to investigate muscular and musculotendinous effects of high intensity eccentric exercise. Twelve accelerometers arranged in a 3 × 4 matrix over the dominant elbow muscles were used to detect MMG activity in 12 healthy participants. Delayed onset muscle soreness was induced by repetitive high intensity eccentric contractions of the wrist extensor muscles. Average rectified values (ARV) as well as percentage of recurrence (%REC) and percentage of determinism (%DET) extracted from recurrence quantification analysis were computed from data obtained during static-dynamic contractions performed before exercise, immediately after exercise, and in presence of muscle soreness. A linear mixed model was used for the statistical analysis. The ARV, %REC, and %DET maps revealed heterogeneous MMG activity over the wrist extensor muscles before, immediately after, and in presence of muscle soreness (P<0.01). The ARVs were higher while the %REC and %DET were lower in presence of muscle soreness compared with before exercise (P<0.05). The study provides new key information on linear and nonlinear analyses of multi-channel MMG recordings of the wrist extensor muscles following eccentric exercise that results in muscle soreness. Recurrence quantification analysis can be suggested as a tool for detection of MMG changes in presence of muscle soreness.


Subject(s)
Muscle, Skeletal/physiopathology , Myalgia/physiopathology , Myography/methods , Wrist/physiopathology , Adult , Exercise/physiology , Female , Humans , Linear Models , Male , Muscle Contraction/physiology , Nonlinear Dynamics , Signal Processing, Computer-Assisted , Time Factors
18.
J Appl Physiol (1985) ; 116(12): 1623-31, 2014 Jun 15.
Article in English | MEDLINE | ID: mdl-24790019

ABSTRACT

Trapezius muscle Hoffman (H) reflexes were obtained to investigate the neural adaptations induced by a 5-wk strength training regimen, based solely on eccentric contractions of the shoulder muscles. Twenty-nine healthy subjects were randomized into an eccentric training group (n = 15) and a reference group (n = 14). The eccentric training program consisted of nine training sessions of eccentric exercise performed over a 5-wk period. H-reflex recruitment curves, the maximal M wave (Mmax), maximal voluntary contraction (MVC) force, rate of force development (RFD), and electromyographic (EMG) voluntary activity were recorded before and after training. H reflexes were recorded from the middle part of the trapezius muscle by electrical stimulation of the C3/4 cervical nerves; Mmax was measured by electrical stimulation of the accessory nerve. Eccentric strength training resulted in significant increases in the maximal trapezius muscle H reflex (Hmax) (21.4% [5.5-37.3]; P = 0.01), MVC force (26.4% [15.0-37.7]; P < 0.01), and RFD (24.6% [3.2-46.0]; P = 0.025), while no significant changes were observed in the reference group. Mmax remained unchanged in both groups. A significant positive correlation was found between the change in MVC force and the change in EMG voluntary activity in the training group (r = 0.57; P = 0.03). These results indicate that the net excitability of the trapezius muscle H-reflex pathway increased after 5 wk of eccentric training. This is the first study to investigate and document changes in the trapezius muscle H reflex following eccentric strength training.


Subject(s)
H-Reflex/physiology , Superficial Back Muscles/physiology , Adaptation, Physiological/physiology , Adult , Electric Stimulation/methods , Exercise/physiology , Female , Foot/physiology , Humans , Male , Muscle Contraction/physiology , Resistance Training/methods , Shoulder/physiology , Young Adult
19.
Motor Control ; 18(3): 297-309, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24457176

ABSTRACT

In the current study we investigated changes in voluntary rhythmic leg movement frequency (freely chosen cycling cadence) and rhythmic movement pattern (tangential pedal force profile) after fatiguing hip flexion and hip extension exercises. Nine healthy individuals performed ergometer cycling at freely chosen cadence and at a cadence of 1 Hz before and after fatiguing hip flexion and hip extension exercises. The freely chosen cadence was not affected after fatiguing exercises. An alteration of key characteristics of the tangential pedal force profile was found during cycling at a cadence of 1 Hz after hip flexion exercise. Thus, minimum tangential pedal force decreased by 12.0 ± 11.3% (p = .006), while maximum tangential pedal force increased by 4.6 ± 4.2% (p = .011), and the phase with negative tangential pedal force increased by 2.6 ± 3.2% (p = .040). In conclusion, novel information was obtained on aspects of rhythmic leg movement behavior in form of pedaling after fatiguing exercise.


Subject(s)
Bicycling/physiology , Muscle Fatigue/physiology , Periodicity , Physical Exertion/physiology , Adult , Exercise/physiology , Exercise Test , Humans , Leg/physiology , Male , Range of Motion, Articular/physiology
20.
J Strength Cond Res ; 27(11): 3045-52, 2013 Nov.
Article in English | MEDLINE | ID: mdl-23442281

ABSTRACT

The purpose of this study was to investigate adaptation mechanisms after 2 test rounds consisting of eccentric exercise using pressure pain imaging of the wrist extensors. Pressure pain thresholds (PPTs) were assessed over 12 points forming a 3 × 4 matrix over the dominant elbow in 12 participants. From the PPT assessments, pressure pain maps were computed. Delayed onset muscle soreness was induced in an initial test round of high-intensity eccentric exercise. The second test round performed 7 days later aimed at resulting in adaptation. The PPTs were assessed before, immediately after, and 24 hours after the 2 test rounds of eccentric exercise. For the first test round, the mean PPT was significantly lower 24 hours after exercise compared with before exercise (389.5 ± 64.1 vs. 500.5 ± 66.4 kPa, respectively; p = 0.02). For the second test round, the PPT was similar before and 24 hours after (447.7 ± 51.3 vs. 458.0 ± 73.1 kPa, respectively; p = 1.0). This study demonstrated adaptive effects of the wrist extensors monitored by pain imaging technique in healthy untrained humans. A lack of hyperalgesia, i.e., no decrease in PPT underlined adaptation after the second test round of eccentric exercise performed 7 days after the initial test round. The present findings showed for the first time that repeated eccentric exercise performed twice over 2 weeks protects the wrist extensor muscles from developing exacerbated pressure pain sensitivity. Thus, the addition of eccentric components to training regimens should be considered to induce protective adaptation.


Subject(s)
Adaptation, Physiological , Exercise/physiology , Muscle, Skeletal/physiology , Myalgia/physiopathology , Pain Threshold/physiology , Adult , Elbow , Female , Forearm , Humans , Male , Muscle Contraction , Pain Measurement , Pressure , Time Factors , Wrist , Young Adult
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