Do sweep rowers symmetrically activate their low back muscles during indoor rowing?

Lumbar muscle adaptations to external perturbations are modulated by trunk posture

PURPOSE

To investigate if the recruitment of different regions within the lumbar extensor muscles in response to unexpected perturbations depends on trunk posture.

METHODS

In a semi-seated posture, healthy adult participants experienced unexpected posterior-anterior trunk perturbations in three different postures: neutral, trunk flexion and left trunk rotation. High-density surface electromyography was used to identify the regional distribution of activation within the lumbar erector spinae muscles. The effect of posture and side (left vs right) on muscle activity and centroid coordinates was investigated at baseline and in response to perturbations.

RESULTS

Higher muscle activity was observed in trunk flexion compared to neutral and rotation postures at baseline (multiple p < 0.001) and in response to the perturbation (multiple p < 0.01). At baseline, the centroid of the electromyographic amplitude distribution was localized more medially in trunk flexion compared to trunk neutral posture (p = 0.003), while activation was localized more laterally in response to the perturbation (multiple p < 0.05). When the trunk was rotated, the electromyographic amplitude distribution was localized more cranially on the left than the right side, both at baseline (p = 0.001) and in response to the perturbation (p = 0.001). Finally, a more lateral location of the centroid on the left side in rotation compared to neutral posture was observed in response to the perturbation (multiple p < 0.001).

CONCLUSIONS

Regional differences in the distribution of electromyographic amplitude indicate that different muscle regions were recruited in different trunk postures and in response to perturbations, possibly based on regional mechanical advantage of the erector spinae muscle fibers.

Total and Regional Body Composition of NCAA Collegiate Female Rowing Athletes

This study explored body composition in female NCAA Division I rowers compared to controls; and the effect of season, boat category, and oar side on body composition. This retrospective analysis of 91 rowers, and 173 age, sex, and BMI-matched controls examined total and regional fat mass (FM), lean mass (LM), bone mineral content (BMC), bone mineral density (BMD), percent body fat (%BF), and visceral adipose tissue (VAT) measured using dual X-ray absorptiometry. Two-sample t-testing was used to assess differences between rowers and controls. Repeated measures ANOVA analyzed differences across seasons. ANOVA analyzed differences between boat categories. Paired t-testing analyzed oar side versus non-oar side. Rowers had greater height (174.2; 164.1 cm), weight (75.2; 62.6 kg), LM (51.97; 41.12 kg), FM (20.74; 19.34 kg), BMC (2.82; 2.37 kg), and BMD (1.24; 1.14 g/cm²); but lower %BF (30.5%; 27.1%), and VAT (168.1; 105.0 g) than controls (p<0.05). Total, arm, and trunk muscle-to-bone ratio were greater in rowers (p<0.001). Rowers demonstrated greater arm LM (5.8 kg; 5.6 kg) and BMC (0.37 kg; 0.36 kg) in Spring compared to Fall (p<0.05). 1V8 rowers had a lower %BF than non-scoring rowers (25.7%; 29.0%; p=0.025). No differences observed between oar sides. These findings will help rowing personnel better understand body composition of female collegiate rowers.

The use of thermal imaging for monitoring the training progress of professional male sweep rowers

This study assesses the thermal profile of the skin in highly trained rowers and investigates the relationship between resting skin temperature (Ts) and the muscle peak torque (PT) measured in statics at the beginning (autumn) and the end (spring) of the preparatory period. Ten professional male sweep rowers, members of the Polish national rowing team, were investigated. A thermal imaging camera was used to analyze the Ts. The PT of the muscles involved in the rowing cycle were measured isometrically. No significant temperature asymmetries were found, except in front of arms after exercise in the spring (p = 0.0228). In contrast, the PT test in the autumn confirmed the significant asymmetry of the knee joint extensors (p = 0.0192). In spring compared to autumn, Ts in many areas of the body were slightly higher, as was PT of underlying muscles. Significant correlations between resting Ts and PT of the underlying muscles were found. Thermal imaging makes it possible to observe changes in skin temperature and symmetry before and after exercise. At this stage, it does not appear to be a method that, without supporting of other methods such as those assessing muscle function, will allow monitoring of training progress.

Are the forearm muscles excited equally in different, professional piano players?

Background and objectives

Professional pianists tend to develop playing-related musculoskeletal disorders mostly in the forearm. These injuries are often due to overuse, suggesting the existence of a common forearm region where muscles are often excited during piano playing across subjects. Here we use a grid of electrodes to test this hypothesis, assessing where EMGs with greatest amplitude are more likely to be detected when expert pianists perform different excerpts.

Methods

Tasks were separated into two groups: classical excerpts and octaves, performed by eight, healthy, professional pianists. Monopolar electromyograms (EMGs) were sampled with a grid of 96 electrodes, covering the forearm region where hand and wrist muscles reside. Regions providing consistently high EMG amplitude across subjects were assessed with a non-parametric permutation test, designed for the statistical analysis of neuroimaging experiments. Spatial consistency across trials was assessed with the Binomial test.

Results

Spatial consistency of muscle excitation was found across subjects but not across tasks, confining at most 20% of the electrodes in the grid. These local groups of electrodes providing high EMG amplitude were found at the ventral forearm region during classical excerpts and at the dorsal region during octaves, when performed both at preferred and at high, playing speeds.

Discussion

Our results revealed that professional pianists consistently load a specific forearm region, depending on whether performing octaves or classical excerpts. This spatial consistency may help furthering our understanding on the incidence of playing-related muscular disorders and provide an anatomical reference for the study of active muscle loading in piano players using surface EMG.

Effects of Visual Biofeedback on Symmetrical Movements During Bridge Exercise With Sling

CONTEXT

Asymmetrical movements of trunk and lower-extremity are common during the bridge exercise on the unstable condition. However, no studies have investigated whether visual biofeedback of pressing pressure on the unstable surface changes muscle activation patterns of trunk and hip extensors and pelvic rotation during the bridge exercise.

OBJECTIVE

To investigate how visual biofeedback of pressing pressure influences symmetrical activity of lumbar and hip extensor and pelvic rotation.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PARTICIPANTS

Twenty healthy males participated in this study.

INTERVENTIONS

The participants performed 2 versions of the bridge exercise: the standard bridge exercise and the bridge exercise with visual biofeedback using amount of pressing pressure on the sling.

MAIN OUTCOME MEASURES

Surface electromyography was used to measure the symmetry (ie, the difference between dominant and nondominant sides) of muscle activation in the bilateral erector spinae, gluteus maximus, and hamstring muscles, and motion sensors were used to assess pelvic rotation. Symmetry of pressing pressure was measured using a tension meter.

RESULTS

The differences between the dominant and nondominant pressing pressures and differences between the electromyography activity of the dominant and nondominant erector spinae, gluteus maximus, and hamstring were significantly smaller during the bridge exercise with visual biofeedback than during the standard bridge exercise (P < .05). In addition, there was significantly less pelvic rotation during the bridge exercise with visual biofeedback than during the standard bridge exercise (P < .05).

CONCLUSIONS

The present findings suggest that visual biofeedback strategy may be a useful method for enhancing the symmetrical activation of the erector spinae, gluteus maximus, and hamstring and for reducing pelvic rotation during the bridge exercise on the unstable surface.

Understanding regional activation of thoraco-lumbar muscles in chronic low back pain and its relationship to clinically relevant domains

BACKGROUND

Altered regional activation of the lumbar extensors has been previously observed in individuals with low back pain (LBP) performing high-effort and fatiguing tasks. It is currently unknown whether similar alterations can be observed during low-effort functional tasks. Similarly, previous studies did not investigate whether side differences in regional activation are present in individuals with LBP. Finally, there is limited evidence of whether the extent of the alteration of regional activation is associated with clinical factors. Therefore, the aim of this study was to investigate whether individuals with LBP exhibit asymmetric regional activation of the thoraco-lumbar extensor muscles during functional tasks, and if the extent of neuromuscular control alteration is associated with clinical and psychosocial outcome domains.

METHODS

21 participants with and 21 without LBP performed five functional tasks (gait, sit-to-stand, forward trunk flexion, shoulder flexion and anterior pelvic tilt). The spatial distribution of activation of the thoraco-lumbar extensor muscles was assessed bilaterally using high-density electromyography. For each side, the distribution of electromyographic (EMG) amplitude was characterized in terms of intensity, location and size. Indices of asymmetry were calculated from these features and comparisons between groups and tasks were performed using ANOVA. The features that significantly differed between groups were correlated with self-reported measures of pain intensity and other outcome domains.

RESULTS

Indices of asymmetry did not differ between participants with and without LBP (p > 0.11). The cranio-caudal location of the activation differed between tasks (p < 0.05), but not between groups (p = 0.64). Participants with LBP showed reduced EMG amplitude during anterior pelvic tilt and loading response phase during gait (both p < 0.05). Pearson correlation revealed that greater pain intensity was associated with lower EMG amplitude for both tasks (R<-0.5, p < 0.05).

CONCLUSIONS

Despite clear differences between tasks, individuals with and without LBP exhibited similar distributions of EMG amplitude during low-effort functional activities, both within and between sides. However, individuals with LBP demonstrated lower activation of the thoraco-lumbar muscles during gait and anterior pelvic tilt, especially those reporting higher pain intensity. These results have implications in the development or refinement of assessment and intervention strategies focusing on motor control in patients with chronic LBP.

Human myoelectric spatial patterns differ among lower limb muscles and locomotion speeds

The spatial distribution of myoelectric activity within lower limb muscles is often nonuniform and can change during different stationary tasks. Recent studies using high-density electromyography (EMG) have suggested that spatial muscle activity may also differ among muscles during locomotion, but contrasting electrode array sizes and experimental designs have limited cross-study comparisons. Here, we sought to determine if spatial EMG patterns differ among lower limb muscles and locomotion speeds. We recorded high-density EMG from the vastus medialis, tibialis anterior, biceps femoris, medial gastrocnemius, and lateral gastrocnemius muscles of 11 healthy subjects while they walked (1.2 and 1.6 m/s) and ran (2.0, 3.0, 4.0, and 5.0 m/s) on a treadmill. To overcome the detrimental effects of cable, electrode, and soft tissue movements on high-density EMG signal quality during locomotion, we applied multivariate signal cleaning methods. From these data, we computed the spatial entropy and center of gravity from the total myoelectric activity within each recording array during the stance or swing phases of the gait cycle. We found heterogeneous spatial EMG patterns evidenced by contrasting spatial entropy among lower limb muscles. As locomotion speed increased, mean entropy values decreased in four of the five recorded muscles, indicating that EMG signal amplitudes were more spatially heterogeneous, or localized, at faster speeds. The EMG center of gravity location also shifted in multiple muscles as locomotion speed increased. Contrasting myoelectric spatial distributions among muscles likely reflect differences in muscle architecture, but increasingly localized activity and spatial shifts in the center of gravity location at faster locomotion speeds could be influenced by preferential recruitment of faster motor units under greater loads.

Timing and Modulation of Activity in the Lower Limb Muscles During Indoor Rowing: What Are the Key Muscles to Target in FES-Rowing Protocols?

The transcutaneous stimulation of lower limb muscles during indoor rowing (FES Rowing) has led to a new sport and recreation and significantly increased health benefits in paraplegia. Stimulation is often delivered to quadriceps and hamstrings; this muscle selection seems based on intuition and not biomechanics and is likely suboptimal. Here, we sample surface EMGs from 20 elite rowers to assess which, when, and how muscles are activated during indoor rowing. From EMG amplitude we specifically quantified the onset of activation and silencing, the duration of activity and how similarly soleus, gastrocnemius medialis, tibialis anterior, rectus femoris, vastus lateralis and medialis, semitendinosus, and biceps femoris muscles were activated between limbs. Current results revealed that the eight muscles tested were recruited during rowing, at different instants and for different durations. Rectus and biceps femoris were respectively active for the longest and briefest periods. Tibialis anterior was the only muscle recruited within the recovery phase. No side differences in the timing of muscle activity were observed. Regression analysis further revealed similar, bilateral modulation of activity. The relevance of these results in determining which muscles to target during FES Rowing is discussed. Here, we suggest a new strategy based on the stimulation of vasti and soleus during drive and of tibialis anterior during recovery.

Comparison of isokinetic knee torque and bioelectrical activity for hamstrings, quadriceps and erector spinae muscles in elite rowers

In sweep rowers, the lower extremities muscle strength translates into the driving force of the boat. Therefore, isokinetic assessment of muscle torque is used by coaches as an indicator of the level of athletes' preparation for competitions. A total of 22 elite sweep rowers performed an isokinetic test of knee joint flexors and extensors, and a test on an asymmetric ergometer with the electromyography measures. Significantly higher quadriceps peak torque was shown during the beginning than the end of the preparatory period (p < 0.05). However, there was no significant knee peak torque difference between the lower extremities (p = 0.398). In the case of the electromyography test of quadriceps, hamstrings and lumbar erector spinae, analysis demonstrated significant bioelectrical activity differences between the sides (p < 0.05). Lower values of quadriceps peak torque at the end of the preparatory period may result from a decrease in the number of power training units during the entire preparatory period. A similar muscle strength between both lower extremities seems to be the correct result in the context of injury prevention. In turn, significant bioelectrical activity differences between the sides possibly are associated with the asymmetric movement pattern in sweep rowers.

Configurable 3D Rowing Model Renders Realistic Forces on a Simulator for Indoor Training

In rowing, rowers need outdoor and indoor training to develop a proficient technique. Although numerous indoor rowing machines have been proposed, none of the devices can realistically render the haptic, visual, and auditory characteristics of an actual rowing scenario. In our laboratory, we developed a simulator to support rowing training indoors. However, rendered forces with the initial rowing model, which was based on a simplified fluid dynamic model that approximated the drag/lift forces, were not perceived realistic enough for indoor training by expert rowers. Therefore, we implemented a new model for the blade–water interaction forces, which incorporates the three-dimensional rotation of the oar and continuously adjusts drag/lift coefficients. Ten expert rowers were asked to evaluate both models for various rowing aspects. In addition, the effect of individualization of model parameters on the perceived realism of rowing forces was elaborated. Based on the answers of the experts, we concluded that the new model rendered realistically resistive forces and ensured a smooth transition of forces within a rowing cycle. Additionally, we found that individualization of parameters significantly improved the perceived realism of the simulator. Equipped with a configurable rowing model, our simulator provides a realistic indoor training platform for rowers.

Design and Test of a Biomechanical Model for the Estimation of Knee Joint Angle During Indoor Rowing: Implications for FES-Rowing Protocols in Paraplegia

Functional electrical stimulation of lower limb muscles during rowing provides a means for the cardiovascular conditioning in paraplegia. The possibility of shaping stimulation profiles according to changes in knee angle, so far conceived as changes in seat position, may help circumventing open issues associated with muscle fatigue and movement coordination. Here, we present a subject-specific biomechanical model for the estimation of knee joint angle during indoor rowing. Anthropometric measurements and foot and seat positions are inputs to the model. We tested our model on two samples of elite rowers; 15 able-bodied, and 11 participants in the Rio 2016 Paralympic games. Paralympic rowers presented minor physical disabilities (LTA-PD classification), enabling them to perform the full rowing cycle (with legs, trunks, and arms). Knee angle was estimated from the rowing machine seat position, measured with a linear encoder, and transmitted wirelessly to a computer. Key results indicate the root mean square error (RMSE) between estimated and measured angles did not depend on group and stroke rate ( ). Significantly greater RMSE values were observed, however, within the rowing cycle ( ), reaching on average 8 deg in the mid-recovery phase. Differences between estimated and measured knee angle values resulted in slightly earlier (5%) detection of knee flexion, regardless of the group and stroke rate considered. Offset of knee extension, knee angle at catch and range of knee motion were identified equally well with our model and with inertial sensors. These results suggest our model describes accurately the movement of knee joint during indoor rowing.

The Impact of the Progressive Efficiency Test on a Rowing Ergometer on White Blood Cells Distribution and Clinical Chemistry Changes in Paralympic Rowers During the Preparatory Stage Before the Paralympic Games in Rio, 2016 - A Case Report

There is a large gap in knowledge regarding research on post-exercise blood changes in disabled athletes. There are relatively few data on adaptive mechanisms to exercise in disabled athletes, including disabled rowers. Two rowers from a Polish adaptive rowing settle TAMix2x that qualified for the Paralympic Games in Rio, 2016 took part in this study. They performed a progressive test on a rowing ergometer until exhaustion. The cardiorespiratory fitness measures, complete blood count, white blood cells' distribution and 30 clinical chemistry variables describing laboratory diagnostic profiles and general health were determined. The extreme effort induced changes in all studied metabolites (glucose, creatinine, urea, uric acid, total and direct bilirubin), albumin, total protein levels in both participants. Furthermore, a post-exercise increase in aspartate transaminase activity, yet a 2-fold decrease during the recovery time in both rowers were found. White blood cell count increased 2-fold after the test. The percentages of natural killer cells were higher and total T lymphocytes were lower after the exercise protocol. There were higher percentages of suppressor/cytotoxic and lower percentages of helper/inducer T lymphocyte subsets in both studied rowers. No changes in B lymphocytes distribution were observed. Lack of inflammatory symptoms during the experiment suggests a high level of rowers' biological adaptation to the physical effort. The different changes in physiological, biochemical and immunological variables are related to the adaptive mechanism to physical exercise allowing for improvement of performance.

Textured insoles affect the plantar pressure distribution while elite rowers perform on an indoor rowing machine

INTRODUCTION

During rowing, foot positioning on the foot stretcher is critical to optimise muscle force transmission and boat propulsion. Following the beneficial effects of textured insoles on gait and balance, this study aims at investigating whether passive stimulation of foot mechanoreceptors induced by these insoles may contribute to improving foot loading pattern and symmetry during indoor rowing.

METHODS

Eleven elite rowers were assessed during controlled training on a standard rowing machine while wearing control, low-density or high-density textured insoles. Plantar pressure and knee and trunk kinematics were measured; performance data were recorded from the machine. Insole effect on kinematic parameters, peak and average values of foot force, contact area and position of centre of pressure was assessed with ANOVA and Bonferroni correction for pair-wise comparisons.

RESULTS

A main effect was observed for force and contact area, with the high-density insoles providing greatest values (P<0.035). No interaction was observed between side and insole (P>0.190), even though symmetry was higher with high-density insoles. Kinematics (P = 0.800) and rowing performance were not affected by insole type; a consistent though not statistically significant increase in mean travelled distance was observed for denser insoles (P>0.21).

CONCLUSION

The high-density textured insoles affected foot loading distribution during indoor rowing. Rowers applied greater foot force and over a greater foot stretcher area with the high-density than the low-density and control insoles. These findings and the methodology applied may be relevant for the understanding and monitoring of rowing performance.