Adam Kawczyński

Delayed onset muscle soreness in neck/shoulder muscles

The aim of the present study is to: (1) induce delayed onset muscle soreness (DOMS) in the neck and shoulder muscles; (2) compare the pressure pain sensitivity of muscle belly with that of musculotendinous tissue after DOMS; (3) examine the gender differences in the development of DOMS. An eccentric shoulder exercise was developed to induce DOMS on neck/shoulder muscles using a specially designed dynamometer. Eccentric shoulder contraction consisted of 5 bouts, each bout lasted 3 min, with 3 min rest period between each bout. The right shoulder was elevating against a downward pressure force of 110% maximal voluntary contraction force exerted by the dynamometer. Pressure pain thresholds (PPT) of 11 sites (seven sites measured were muscle belly and four sites were myotendinous area) on neck/shoulder region were measured before, immediately after, 24 and 48 h after exercise. Pain intensity, pain area and index of McGill pain questionnaire were assessed and all were increased after exercise. DOMS was induced in the shoulder muscles. PPT was significantly decreased and reached lowest values at 24 h. The muscle belly sites are more sensitive to pain than the musculotendinous sites. No gender differences were found in any of the parameters used to assess the development of DOMS. DOMS did not distribute evenly in the neck/shoulder region. Soreness after exercise in the neck and shoulder seems not to be among the conditions that produce predominant musculoskeletal pain in females.

Mechanomyography and electromyography during and after fatiguing shoulder eccentric contractions in males and females.

The aim of this study was to investigate changes in mechanomyographic (MMG) and the surface electromyographic (EMG) signals during and after fatiguing shoulder eccentric contractions in a group consisting of 12 males and 12 females. Exerted force, MMG, EMG, pain and rate of perceived exertion were assessed before, during and after repeated high‐intensity eccentric exercises. Bouts of eccentric contractions caused a decrease in the exerted force for males (P<0.05) and an increase in the rate of perceived exertion and pain for both genders (P<0.05). During eccentric exercise, the root mean square (RMS) values of the MMG signal increased (P<0.05). The mean power frequency (MPF) values of the EMG signal decreased at the end of each eccentric bout for both genders (P<0.05); the decrease was higher for females compared with males (P<0.05). Immediately after eccentric exercise in static abduction of the upper limbs, the MMG RMS and MPF values increased (P<0.05). The present study showed that (1) neuromuscular changes associated with pain and changes in muscle stiffness and (2) changes in motor units strategy during fatigue development in shoulder muscle are reflected in the MMG and EMG signals.

Tensegrity principle in massage demonstrated by electro- and mechanomyography

Based on a tensegrity principle, direct or indirect connections between fascia or muscles which stretch the aponeurosis or intermuscular septum may allow the transfer of tension over long distances, without loss of muscle force produced during rest and activity. The present study aimed to test an effect of massage on electrical (EMG) and mechanical (MMG) activities of a muscle lying distant, but indirectly connected to, the massaged muscle. Thirty-three healthy men participated in the study. To record the activity of the middle deltoid muscle the brachioradialis was massaged, and for the tensor fasciae latae-the peroneal muscles were massaged. An EMG/MMG hybrid probe was used to detect EMG and MMG signals from the middle deltoid and tensor fasciae latae muscles. The EMG amplitude increased during massage in the tensor fasciae lata only, while the MMG amplitude increased significantly in both muscles. It was concluded that there was an electrical as well as a mechanical response of muscle connected indirectly by structural elements with the muscle being massaged indicating an application for the tensegrity principle in massage therapy. It also has a practical importance, because it provides a means for a physiotherapist to influence adverse muscle tension by massaging another distant muscle.

Sensory mapping of the upper trapezius muscle in relation to consecutive sessions of eccentric exercise.

Abstract Kawczyński, A, Samani, A, Fernández-de-las-Peñas, C, Chmura, J, and Madeleine, P. Sensory mapping of the upper trapezius muscle in relation to consecutive sessions of eccentric exercise. J Strength Cond Res 26(6): 1577–1583, 2012—The aim of this study was to evaluate the changes in pressure pain sensitivity maps in untrained subjects over 2 subsequent sessions of eccentric exercise (ECC) expected to result in (a) delayed onset muscle soreness (DOMS) and (b) adaptation/recovery, respectively. Eleven healthy male subjects participated in this study. Pressure pain threshold (PPT), rate of perceived exertion (RPE), pain intensity, soreness area drawing, maximal voluntary contraction (MVC), and shoulder range of motion were assessed in session 1 before, immediately after, and 24 hours after ECC. The ECC protocol that was used to induce DOMS consisted of 50 eccentric contractions of the right shoulder that were divided into 5 bouts, including 10 contractions at MVC level separated by a 2-minute resting period. Session 2 was identical to session 1 and performed exactly 1 week later. There was only a significant increase in the RPE assessed before the exercise and 24 hours after the exercise in session 1 (p = 0.001). The average PPT only decreased significantly from before the exercise (660.2 ± 76.2 kPa) to 24 hours after the exercise (435.6 ± 59.3 kPa) in session 1 (p = 0.016). The present study confirmed a heterogeneous distribution of mechanical sensitivity before and after sessions of ECC. The first session of ECC underlined increased mechanical sensitivity because of DOMS, whereas the second session reflected an adaptation process. Our results support the potential role of ECC bouts in training regimens.

Changes of Reaction Time and Blood Lactate Concentration of Elite Volleyball Players During a Game

Changes of Reaction Time and Blood Lactate Concentration of Elite Volleyball Players During a Game The purpose of this study was to investigate changes in reaction time of elite volleyball players during a game. Fourteen volleyball players participated in the study. Reaction time was measured using the Optojump system. In addition, blood lactate concentration was assessed to monitor physiological load during the game. All measurements were performed during a pre-game test and during sets 1, 2, 3 and 4. Reaction time during set 1 decreased significantly by 13,3 % compared with pre-game values, from 600 ms during the pre-game test to 520 ms during set 1 (p<0,05). Blood lactate concentration increased significantly during set 1, 2, 3 and 4 compared with pre-game conditions (p<0,05). Reaction time stays in the first phase of its changes pattern and elite volleyball players do not reach psychomotor fatigue threshold throughout the game.

Principle component analysis of exposure variation analysis during computer work at presence of delayed onset muscle soreness

Eleven healthy volunteers took part in three sessions where computer work was performed for 10 min in each session. The recordings were made on two consecutive days. After the first session, the subjects underwent a series of high intensity eccentric exercises of shoulder elevation to induce muscle soreness. The second session was performed immediately after the exercises and third session 24 hours after the exercise. Surface electromyography (EMG) of descending and ascending trapezius, deltoideus anterior and serratus anterior was recorded. Exposure variation analysis (EVA) centroid and marginal distribution was computed. Principle component analysis (PCA) was performed on both cases. Describing more than 80% of variance, first eight components for EVA marginal distributions and first four ones for EVA centroid were picked to be investigated. The sole EVA amplitude levels played a practically significant role to describe the variation in EVA marginal distribution. However, a significant pattern of load redistribution to superficial muscles was not found. This may suggest investigating the role of deep muscles in redistribution of load during computer work in response to high level eccentric contractions.

Supervised neuro-fuzzy biofeedback for computer users

The design of an advanced biofeedback system was introduced using neuro-fuzzy concept. Eleven healthy volunteers took part in six sessions over two weeks in which computer work was performed for 10 min. The six sessions were divided into two identical parts where each part was taken place in two consecutive days. After the first session, the subjects underwent excessive eccentric exercises of shoulder elevation to induce muscle soreness. The second session was performed immediately after the exercises and third session 24 hours after the exercises. The second part was performed exactly one week after the first part. Surface electromyography (EMG) of descending and ascending trapezius, deltoideus anterior and serratus anterior was recorded. Linear and nonlinear indices of muscular load were calculated from EMG signals. The first session was utilized as the benchmark of normal muscle condition during computer work and all the rest as mal-functioning/altered condition. A neuro-fuzzy system was trained and tested to discriminate between the first session and all the rest. Using a greedy forward search strategy most discriminative features were found. A high sensitivity ~90% but a low specificity ~60% was observed. It was concluded that apart from the trapezius, the deltoideus and serratus anterior should also benefit from a biofeedback design. Combining of such system with timing constraint on biofeedback alarming can render a viable biofeedback system aiming at preventing musculoskeletal disorders.

Trapezius viscoelastic properties are heterogeneously affected by eccentric exercise

OBJECTIVES The aim of this study was to investigate the influence of eccentric exercise (ECC) on the spatial mapping of muscle stiffness and creep of the upper trapezius, using a quantitative myotonometry device. DESIGN Two groups of 16 subjects participated in the experimental sessions. In part A, the test-retest reliabilities of muscle stiffness and creep were assessed. In part B, muscle stiffness and muscle creep were mapped before, immediately after and 24h after ECC when post-exercise soreness had developed. METHODS The ECC protocol consisted of 50 eccentric contractions divided into 5 bouts of 10 contractions at maximum force level. RESULTS The relative reliabilities of stiffness and creep measurements were found to be substantial to almost perfect. Muscle stiffness for musculotendinous sites increased at 24h after ECC while it decreased for muscle belly immediately after and 24h after ECC. Muscle creep for musculotendinous sites decreased, and for muscle belly sites increased, immediately after and 24h after ECC. CONCLUSIONS For the first time, the present study showed sign of discrepancies in the effects of ECC on muscle stiffness and creep, underlining opposite changes in the musculotendinous and muscle belly viscoelastic properties of upper trapezius.

Blood lactate concentrations in elite Polish 100 m sprinters

The main objective of this study was to show and analyse the changes in blood lactate concentrations in Polish elite sprinters. The study sample was comprised of 9 top male sprinters and 8 top female sprinters, all finalists from the Polish national championships. Blood lactate concentrations were evaluated with the use of a Lactate Scout measuring device. The measurements were taken pre-exercise and at 1, 5 and 10 minutes post-exercise. Before warm-up, the mean blood lactate concentration in male subjects was 1.40 ± 0.24 mmol/L and for female subjects 1.23 ± 0.24 mmol/L. During the first minute of recovery, the post-exercise lactate concentration rose to 9.38 ± 2.18 mmol/L in male sprinters and to 6.73 ± 2.48 mmol/L in female sprinters. Five minutes after the end of the 100 m sprint, the lactate level for females was 11.01 ± 2.14 mmol/L and for males 10.11 ± 0.99 mmol/L. Lactate concentrations at 10 minutes post-exercise reached 9.51 ± 1.23 mmol/L for male sprinters and 9.09 ± 1.46 mmol/L for female sprinters. The observed blood lactate concentration changes in Polish elite sprinters after a 100 m race provide new information regarding recovery dynamics which can be useful in designing sprint training.

The Impact of Post Activation Potentiation on Achilles Tendon Stiffness, Elasticity and Thickness among Basketball Players

The purpose of this study is to examine and further understand the effects of post activation potentiation on Achilles tendon (AT) thickness, elasticity and stiffness among basketball players. Basketball is one of the world’s most popular and widely viewed sports. One of the main factors which athletes depend on during their performance is elastic energy coming straight from the AT. Contractile activity increases the muscular force and is known in science as post activation potentiation (PAP). Twelve basketball players (aged 21.3 ± 2.1 years) from the first Polish league took part in this study. The PAP session consisted of single repetitions of the squat with loads corresponding to 60%, 70%, 80%, 90% and 100% of 1 repetition maximum (RM). The measurement method for AT thickness was ultrasonography and for the elasticity and stiffness was myotonometry. The measurements were taken before and immediately after PAP training session. Obtained results: AT stiffness increased significantly from the baseline post exercise, while AT thickness and elasticity decreased after the physical effort. The exercise in PAP caused significant changes in stiffness, elasticity and thickness of the AT.