Validity and Reliability of Smartphone App for Evaluating Postural Adjustments during Step Initiation.

The evaluation of anticipatory postural adjustments (APAs) requires high-cost and complex handling systems, only available at research laboratories. New alternative methods are being developed in this field, on the other hand, to solve this issue and allow applicability in clinic, sport and hospital environments. The objective of this study was to validate an app for mobile devices to measure the APAs during gait initiation by comparing the signals obtained from cell phones using the Momentum app with measurements made by a kinematic system. The center-of-mass accelerations of a total of 20 healthy subjects were measured by the above app, which read the inertial sensors of the smartphones, and by kinematics, with a reflective marker positioned on their lumbar spine. The subjects took a step forward after hearing a command from an experimenter. The variables of the anticipatory phase, prior to the heel-off and the step phase, were measured. In the anticipatory phase, the linear correlation of all variables measured by the two measurement techniques was significant and indicated a high correlation between the devices (APAonset: r = 0.95, p < 0.0001; APAamp: r = 0.71, p = 0.003, and PEAKtime: r = 0.95, p < 0.0001). The linear correlation between the two measurement techniques for the step phase variables measured by ques was also significant (STEPinterval: r = 0.56, p = 0.008; STEPpeak1: r = 0.79, p < 0.0001; and STEPpeak2: r = 0.64, p < 0.0001). The Bland−Altman graphs indicated agreement between instruments with similar behavior as well as subjects within confidence limits and low dispersion. Thus, using the Momentum cell phone application is valid for the assessment of APAs during gait initiation compared to the gold standard instrument (kinematics), proving to be a useful, less complex, and less costly alternative for the assessment of healthy individuals.

Validation of a 3D Camera System for Cycling Analysis.

BACKGROUND: Kinematic analysis aimed toward scientific investigation or professional purposes is commonly unaffordable and complex to use. OBJECTIVE: The purpose of this study was to verify concurrent validation between a cycling-specific 3D camera and the gold-standard 3D general camera systems. METHODS: Overall, 11 healthy amateur male triathletes were filmed riding their bicycles with Vicon 3D cameras and the Retul 3D cameras for bike fitting analysis simultaneously. All 18 kinematic measurements given by the bike fitting system were compared with the same data given by Vicon cameras through Pearson correlation (r), intraclass correlation coefficients (ICC), standard error measurements (SEM), and Bland-Altman (BA) analysis. Confidence intervals of 95% are given. RESULTS: A very high correlation between cameras was found on six of 18 measurements. All other presented a high correlation between cameras (between 0.7 and 0.9). In total, six variables indicate a SEM of less than one degree between systems. Only two variables indicate a SEM higher than two degrees between camera systems. Overall, four measures indicate bias tendency according to BA. CONCLUSIONS: The cycling-specific led-emitting 3D camera system tested revealed a high or very high degree of correlation with the gold-standard 3D camera system used in laboratory motion capture. In total, 14 measurements of this equipment could be used in sports medicine clinical practice and even by researchers of cycling studies.

Diagnostic Validity of an Isokinetic Testing to Identify Partial Anterior Cruciate Ligament Injuries.

OBJECTIVE: To assess the diagnostic validity of an isokinetic testing to detect partial injuries on the anterior cruciate ligament (ACL). DESIGN: Prospective diagnostic study. SETTINGS: Orthopedic clinic, physiotherapy clinic, orthopedic hospital, and diagnostic/image clinic. PARTICIPANTS: Consecutive patients (n = 29) with unilateral knee complaint submitted to physical examination, magnetic resonance images (MRIs), and isokinetic testing prior to surgery of ACL reconstruction. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The isokinetic torque curves data from extensor and flexor muscles were converted to frequency domain by fast Fourier transformation and compared with healthy contralateral limb. Differences were categorized as unstable knees and these conclusions were compared with patient's physical examinations (doctor's conclusion on ACL integrity) and MRIs (as the radiologist conclusions on ACL integrity). After surgery, all intraoperatively confirmed partial injured patient's data were collected. The diagnostic accuracy measures to compare the conclusions of all 3 professionals included sensitivity, specificity, positive predictive value, negative predictive value, disease prevalence, positive likelihood ratio, and accuracy-all using a confidence interval of 95%. RESULTS: Compared with MRI, the sensitivity of isokinetic test for an ACL partial injury was 90.00%, specificity 83.33%, positive predictive value 52.94%, negative predictive value 97.56%, and accuracy 84.48%. Compared with physical examination, the sensitivity of isokinetic test for an ACL partial injury was 85.71%, specificity 78.43%, positive predictive value 35.29%, negative predictive value 97.56%, and accuracy 79.31%. CONCLUSIONS: This method of isokinetic data analysis through fast Fourier transformation can be used to improve diagnostic accuracy of a difficult detection injury. Even present, a partial ACL injury can produce a stable knee during isokinetic testing and could be used to detect candidates for conservative treatment based on strengthening exercises, reducing surgery risks, and financial and social impact on patient's life.

Low-Back Pain and Knee Position-Related Differences on Postural Control Measures During a One-Legged Stance in Athletes.

CONTEXT: Chronic low-back pain (CLBP) may be associated with changes in postural balance in athletes as poor postural control during sports practice. OBJECTIVE: To compare the postural control of athletes with and without CLBP during 2 one-legged stance tasks and identify the center of pressure (COP) cutoff values to determine the main differences. Designed: A cross-sectional study. SETTING: Laboratory of functional evaluation and human motor performance. PARTICIPANTS: A total of 56 male athletes, 28 with and 28 without CLBP (mean age = 26 y). INTERVENTION: The one-legged stance with knee extension and with the knee at 30° flexion tasks were measured and analyzed on a force platform. The participants completed three 30-second trials (30 s of rest between each trial). MAIN OUTCOME MEASURES: The COP parameters: the area of COP, mean COP sway velocity in both the anteroposterior and mediolateral directions, and total COP displacement were computed, and a receiver operating characteristics curve analysis was applied to determine the group differences. RESULTS: Athletes with CLBP had poorer postural control (P < .01) in both tasks. The 30° knee flexion reported more postural instability than the knee extension for all COP parameters (a large effect size d = 0.80).The knee extension cutoffs identified were >7.1 cm2 for the COP area, >2.6 cm/s for the COP sway velocity in the anterior-posterior direction, and >3.2 cm/s for the mediolateral direction. Whereas, the 30° knee flexion cutoffs were >10.9 cm2 for the COP area, >2.9 cm/s for the COP sway velocity in the anterior-posterior direction, and >4.1 cm/s for the mediolateral direction. Both measures showed enough sensitivity and specificity (ie, area under the curve = 0.88 in and 0.80, respectively) to discriminate both groups. CONCLUSIONS: The athletes with CLBP had poorer postural control than the healthy athletes and obtained specific cutoff scores from the COP values.

Test-retest reliability of the different dynamometric variables used to evaluate pelvic floor musculature during the menstrual cycle.

OBJECTIVE: The aim of this study was to evaluate the reliability of different dynamometric variables of the pelvic floor muscles (PFM) in healthy women during different periods of menstrual cycle. MATERIALS AND METHODS: Vaginal dynamometric equipment was developed by the authors and its reproducibility was tested. The PFM contractions of 20 healthy women were collected by two independent examiners over three consecutive weeks, always on the same day, with a seven-day interval between readings, starting from the first day after the end of the menstrual period. For the measurements, the branch of the dynamometer was positioned first on the sagittal plane and then on the frontal plane. Baseline, peak time, maximum PFM strength, impulse contraction, and average contraction force were calculated. Reproducibility was tested using the intra-class correlation coefficient (ICC) and standard error of measurement. Repeated-measures ANOVA was used to compare the data from different days. RESULTS: For intra-day and inter-day reliability between examiners, all the parameters collected on the sagittal plane presented good and excellent reproducibility (ICC2,1 = 0.60 to 0.98), whereas reproducibility on the frontal plane was respectively poor and excellent (ICC2,1 = 0.23 to 0.97). The ANOVA revealed significant differences between sessions only for the impulse of contraction for the sagittal (P = 0.005) and frontal (P = 0.03) planes. CONCLUSIONS: Time and contraction force parameters of the PFM are not influenced by hormonal alterations that occur during the menstrual cycle. The impulse of contraction was the only variable to demonstrate a significant difference between the first and second week of the data collection protocol. The baseline, maximum strength value, impulse of contraction, and average contraction force variables presented good to excellent reproducibility and can be safely used as a method of PFM evaluation.

Muscle fiber conduction velocity and EMG amplitude of the upper trapezius muscle in healthy subjects after low-level laser irradiation: a randomized, double-blind, placebo-controlled, crossover study.

Although low-level laser therapy (LLLT) is an important resource for the treatment of non-specific neck pain patients, the dose which presents the greatest therapeutic potential for the treatment of this pathology is still unclear. The present study aimed to evaluate the immediate effect of LLLT on the muscle fiber conduction velocity (MFCV) and electromyographic activity (EMG) of the upper trapezius (UT) muscle in healthy individuals. A total of 20 healthy subjects were enrolled in a randomized, double-blind, crossover study. Active LLLT (820 nm wavelength, 30 mW, energy total 18 J) or placebo LLLT (pLLLT) was delivered on the UT muscle. Each subject was subjected to a single session of active LLLT and pLLLT. Surface electromyography (sEMG) signal of the UT muscle was recorded during five different step contractions of shoulder elevation force (10-30% maximal voluntary contraction) pre- and post-LLLT irradiation. The values of MFCV and sEMG global amplitude (RMSG) were used to calculate the effects of LLLT. The results showed no difference in the MFCV comparing the LLLT and pLLLT groups (F = 0.72 p = 0.39, η p2 = 0.004). However, a significant difference was observed in the RMSG between the LLLT and pLLLT (F 1,2 = 16.66; P < 0.0001, η p2 = 0.09). Individuals who received active LLLT presented a significant decrease in RMSG after laser application (F = 61.28; p < 0.0001, η p2 = 0.43). In conclusion, the 820 nm LLLT, with energy total of 18 J, did not alter the MFCV but significantly reduced the sEMG signal amplitude of the upper trapezius muscle in healthy subjects to a level of up to 30% of maximal voluntary contraction.

Immediate Effect of Acupuncture on Electromyographic Activity of the Upper Trapezius Muscle and Pain in Patients With Nonspecific Neck Pain: A Randomized, Single-Blinded, Sham-Controlled, Crossover Study.

OBJECTIVE: The objective of this study was to assess changes in upper trapezius myoelectric activity and pain in patients with nonspecific neck pain after a single session of acupuncture (ACP). METHODS: A blinded randomized clinical trial was conducted. Fifteen patients with nonspecific neck pain and 15 healthy participants were enrolled in a randomized, single-blinded, crossover study. Each participant was subjected to a single session of ACP and sham acupuncture (SACP). The electromyography (EMG) signal of the upper trapezius muscle was recorded during different step contractions of shoulder elevation force (15%-30% maximal voluntary contraction) before and after ACP treatment. RESULTS: Significant effects were confirmed after the treatment (ACP and SACP) for Numeric Rating Scale scores (F1,28 = 51.61; P < .0001) and pain area (F1,2 = 32.03; P < .0001). Significant decreases in the EMG amplitude were identified for the nonspecific neck pain group (NPG) (F1,112 = 26.82; P < .0001) and the healthy participant group (HPG) (F1,112 = 21.69; P < .0001) after ACP treatment. No differences were identified between the ACP and SACP treatment protocols for Numeric Rating Scale score (NPG: F1,28 = 0.95; P = .33), pain area (NPG: F1,28 = 1.97; P = .17), or EMG amplitude (NPG: F1,112 = 0.47; P = .49; HPG: F1,112 = 0.75; P = .38). CONCLUSION: The effect of ACP at acupoints triple energizer 5 and large intestine 11 triple energizer 5, or in close proximity, contributes to pain relief among patients with nonspecific neck pain. The electromyographic analysis indicated a greater resistance to muscle fatigue and decrease of activity of the upper trapezius muscle among healthy participants and patients with nonspecific neck pain.

Muscle Activation During Pilates Exercises in Participants With Chronic Nonspecific Low Back Pain: A Cross-Sectional Case-Control Study.

OBJECTIVE: To determine the amplitude of the electromyographic activity of trunk muscles during Pilates exercises in women with and without chronic low back pain (LBP). DESIGN: Case-control study. SETTING: University physical therapy clinic. PARTICIPANTS: Women (N=60) divided into an LBP group and a control group. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Amplitude of the electromyographic activity (root mean square values) of the gluteus maximus and external oblique muscles collected during 3 Pilates exercises: Shoulder Bridge performed on the mat, and Hip Roll and Breathing performed in equipment. Pain intensity was assessed in the LBP group. RESULTS: The amplitude of the electromyographic activity was similar between groups (P≥.05). For both groups, the amplitude of the gluteus maximus was higher in the Shoulder Bridge exercise compared with the Hip Roll with 2 springs (control group: mean difference [MD]=.18; 95% confidence interval [CI], .05-.41; LBP group: MD=.29; 95% CI, .16-.31) and the Breathing exercise (control group: MD=-.40; 95% CI, -.55 to -.26; LBP group: MD=-.36; 95% CI, -.52 to -.20). The amplitude of the external oblique muscle was higher in the Shoulder Bridge compared with the Hip Roll with 2 springs (control group: MD=.13; 95% CI, .05-.21; LBP group: MD=.18; 95% CI, .03-.33). Pain intensity increased after exercises, but this increase was lower for the mat exercises. CONCLUSIONS: Similar muscle activation between groups was found. The findings suggest that mat exercises caused less pain and a greater difference in the amplitude of muscle activation compared with the equipment-based exercises.

Trunk Muscle EMG During Intermediate Pilates Mat Exercises in Beginner Healthy and Chronic Low Back Pain Individuals.

OBJECTIVE: The purpose of this study was to compare the electromyographic pattern of core muscles during intermediate Pilates mat exercises between healthy people and those with low back pain. METHODS: We evaluated healthy participants (n = 19; mean ± standard deviation [SD]: age 28 ± 8 years, body mass 65 ± 10 kg, height 160.0 ± 9.1 cm) and a low back pain group (n = 13; mean ± SD: age 30 ± 9 years, body mass 67 ± 12 kg, height 170.0 ± 6.6 cm). Electromyographic analysis assessed the multifidus, external oblique, internal oblique, and rectus abdominis muscles during classical Pilates exercises (single leg stretch, criss-cross, and dead bug). We calculated the root mean square normalized by maximum voluntary contraction, and the time of peak activation was provided by a linear envelope and normalized by the total movement cycle. RESULTS: The criss-cross exercise presented the highest values of root mean square for trunk flexors (rectus abdominis and oblique) compared with the other exercises, followed by the single leg stretch and the dead bug, which had similar muscle activation. The single leg stretch presented more activation of the rectus abdominis and oblique, whereas the criss-cross and dead bug created more activation of the oblique compared with the multifidus and rectus. CONCLUSIONS: The Pilates exercises presented different muscle recruitment patterns, and allowed the activation of the lumbopelvic stabilizing muscles even in the first session for healthy individuals and those with chronic low back pain.

High oxygen extraction and slow recovery of muscle deoxygenation kinetics after neuromuscular electrical stimulation in COPD patients.

PURPOSE: It was hypothesized that patients with chronic obstructive pulmonary disease (COPD) would exhibit a slow muscle deoxygenation (HHb) recovery time when compared with sedentary controls. METHODS: Neuromuscular electrical stimulation (NMES 40 and 50 mA, 50 Hz, 400 µs) was employed to induce isometric contraction of the quadriceps. Microvascular oxygen extraction (µO2EF) and HHb were estimated by near-infrared spectroscopy (NIRS). Recovery kinetic was characterized by measuring the time constant Tau (HHb-τ). Torque and work were measured by isokinetic dynamometry in 13 non-hypoxaemic patients with moderate-to-severe COPD [SpO2 = 94.1 ± 1.6 %; FEV1 (% predict) 48.0 ± 9.6; GOLD II-III] and 13 age- and sex-matched sedentary controls. RESULTS: There was no desaturation in either group during NMES. Torque and work were reduced in COPD versus control for 40 and 50 mA [torque (Nm) 50 mA = 28.9 ± 6.9 vs 46.1 ± 14.2; work (J) 50 mA = 437.2 ± 130.0 vs. 608.3 ± 136.8; P < 0.05 for all]. High µO2EF values were observed in the COPD group at both NMES intensities (corrected by muscle mass 50 mA = 6.18 ± 1.1 vs. 4.68 ± 1.0 %/kg; corrected by work 50 mA = 0.12 ± 0.05 vs. 0.07 ± 0.02 %/J; P < 0.05 for all). Absolute values of HHb-τ (50 mA = 31.11 ± 9.27 vs. 18.08 ± 10.70 s), corrected for muscle mass (50 mA 3.80 ± 1.28 vs. 2.05 ± 1.45 s/kg) and corrected for work (50 mA = 0.08 ± 0.04 vs. 0.03 ± 0.02 s/J) were reduced in COPD (P < 0.05 for all). The variables behaviour for 40 mA was similar to those of 50 mA. CONCLUSIONS: COPD patients exhibited a slower muscle deoxygenation recovery time after NMES. The absence of desaturation, low torque and work, high µO2EF and high values for recovery time corrected by muscle mass and work suggest that intrinsic muscle dysfunction has an impact on muscle recovery capacity.

Age-related differences on low back pain and postural control during one-leg stance: a case-control study.

BACKGROUND AND PURPOSE: The prevalence of chronic low back pain (CLBP) is higher in older than in younger adults and is associated with poor postural control and falls. The objective of this study was to compare the postural control of younger and older subjects with and without CLBP during a one-leg stance. METHODS: Twenty subjects with and 20 subjects without nonspecific CLBP participated in the study. Each group contained 10 younger (50% males; mean age: 31 years) and 10 older adults (50% males; mean age 71 years). The subjects performed three 30-s trials of a one-leg stance on a force platform. Balance parameters were computed to quantify postural control, including center of pressure (COP) area, mean velocity, and mean frequency in the anteroposterior and mediolateral directions. RESULTS: Participants with CLBP presented significantly poorer balance (P < 0.05) than participants without CLBP. The effect size was large for younger adults (d = 1.44) and small for older adults (d = 0.40). Older adults with CLBP presented poorer balance than younger adults with CLBP (large effect size, d = 1.24). CONCLUSIONS: The findings indicate that CLBP affects the balance of both younger and older adults, and that the age-related changes also affect balance and modify the magnitude of CLBP effects on balance.

Effect of diabetic neuropathy severity classified by a fuzzy model in muscle dynamics during gait.

BACKGROUND: Electromyography (EMG) alterations during gait, supposedly caused by diabetic sensorimotor polyneuropathy, are subtle and still inconsistent, due to difficulties in defining homogeneous experimental groups with a clear definition of disease stages. Since evaluating these patients involve many uncertainties, the use of a fuzzy model could enable a better discrimination among different stages of diabetic polyneuropathy and lead to a clarification of when changes in muscle activation start occurring. The aim of this study was to investigate EMG patterns during gait in diabetic individuals with different stages of DSP severity, classified by a fuzzy system. METHODS: 147 subjects were divided into a control group (n = 30) and four diabetic groups: absent (n = 43), mild (n = 30), moderate (n = 16), and severe (n = 28) neuropathy, classified by a fuzzy model. The EMG activity of the vastus lateralis, tibialis anterior, and gastrocnemius medialis were measured during gait. Temporal and relative magnitude variables were compared among groups using ANOVA tests. RESULTS: Muscle activity changes are present even before an established neural involvement, with delay in vastus lateralis peak and lower tibialis anterior relative magnitude. These alterations suggest an impaired ankle shock absorption mechanism, with compensation at the knee. This condition seems to be more pronounced in higher degrees of neuropathy, as there is an increased vastus lateralis activity in the mild and severe neuropathy groups. Tibialis anterior onset at terminal stance was anticipated in all diabetic groups; at higher degrees of neuropathy, the gastrocnemius medialis exhibited activity reduction and peak delay. CONCLUSION: EMG alterations in the vastus lateralis and tibialis anterior occur even in the absence of diabetic neuropathy and in mild neuropathic subjects, seemingly causing changes in the shock absorption mechanisms at the heel strike. These changes increase with the onset of neural impairments, and the gastrocnemius medialis starts presenting altered activity in the later stages of the disease (moderate and severe neuropathy). The degree of severity of diabetic neuropathy must be taken into account when analyzing diabetic patients' biomechanical patterns of locomotion; we recommend the use of a fuzzy model for classification of disease stages.

Pelvic floor muscle training program increases muscular contractility during first pregnancy and postpartum: electromyographic study.

AIMS: The aim of this study was to evaluate the effect of a training program over both pelvic floor muscles contractility and urinary symptoms in primigravid pregnant and postpartum primiparous women. PATIENTS AND METHODS: A clinical, prospective and blinded trial was conducted with 33 women divided into three groups: (G1) 13 primigravid pregnant women; (G2) 10 postpartum primiparous women (49.3 ± 5.84 days), after vaginal delivery with right mediolateral episiotomy; (G3) 10 postpartum primiparous women (46.3 ± 3.6 days), after cesarean section delivery. The evaluation was carried out using digital palpation (Modified Oxford Grading Scale), pelvic floor electromyography and, for the investigation of urinary symptoms, validated questionnaires (International Consultation on Incontinence Questionnaire-short form-ICIQ-UI SF and International Consultation on Incontinence Questionnaire Overactive Bladder-ICIQ-OAB). The protocol consisted of 10 individual sessions carried out by the physiotherapist through home visits, three times a week, with 60 min duration each. The statistical analysis was performed using ANOVA and Spearman's correlation coefficient. RESULTS: The pelvic floor muscle contractility increased after the training program (P = 0.0001) for all groups. Decreases in the scores of both ICIQ-UI SF (P = 0.009) and ICIQ-OAB (P = 0.0003) were also observed after training. CONCLUSION: Pelvic floor muscle training is an effective means for the increase in its own contractility in both primigravid pregnant and primiparous postpartum women, accompanied with a concomitant decrease in urinary symptoms.

Are transversus abdominis/oblique internal and pelvic floor muscles coactivated during pregnancy and postpartum?

AIM: The aim of this study was to simultaneously evaluate both transversus abdominis/internal oblique (Tra/IO) and pelvic floor muscles (PFM) during isometric exercises in nulliparous, pregnant, and postpartum women. METHODS: The study included 81 women divided into four groups: (G1) nulliparous women without urinary symptoms (n = 20); (G2) primigravid pregnant women with gestational age ≥24 weeks (n = 25); (G3) primiparous postpartum women after vaginal delivery with right mediolateral episiotomy (n = 19); (G4) primiparous postpartum women after cesarean section delivery, with 40 to 60 days of postpartum (n = 17). The assessment consisted of simultaneous surface electromyography (EMGs) of the PFM and Tra/IO, during three isometric maximum voluntary contractions. RESULTS: Only nulliparous women presented significant simultaneous Tra/IO and PFM co-activation when asked to contract PFM (P = 0.0007) or Tra/IO (P = 0.00001). CONCLUSIONS: There is co-activation of the transversus abdominis/internal oblique and the pelvic floor muscles in young, asymptomatic nulliparous women. This pattern was modified in primigravid pregnant and primiparous postpartum women regardless of the delivery mode.

Is there correlation between electromyography and digital palpation as means of measuring pelvic floor muscle contractility in nulliparous, pregnant, and postpartum women?

AIMS: The continence mechanisms depend on the integrity of the pelvic floor muscles. It is therefore important to find simple, reliable, and safe methods to assess its contractility in a clinical setting. This study aims to investigate if digital palpation of the pelvic floor muscles presents correlation with its electromyographic activity. METHODS: The sample consisted of 307 women with mean age of 23.93 years, including 39 nulliparous, 117 primigravid pregnant, 64 primiparous, in post-vaginal delivery, and 87 primiparous women, in post-cesarean section delivery. The assessment consisted of both digital palpation and surface electromyography. One, and the same, highly skilled and experienced physiotherapist, who was able to classify the different grades of contractility accurately, performed digital palpation using the Modified Oxford Grading Scale. Surface electromyography was performed using an intravaginal probe. For electromyography evaluation, three contractions of 5 sec each were recorded, and an average of three Root Mean squares was considered for analysis. Spearman's Coefficient, Jonckheere-Terpstra Test, Kruskal-Wallis as well as Dunn Test were used for statistical analysis. RESULTS: The strong correlation found between the two methods (P < 0.001) indicates that both digital palpation and electromyography can be used in everyday practice, both for clinical use and scientific research, although both have their specific limitations and requirements to avoid the risk of biases. CONCLUSION: There was a correlation between pelvic floor muscle contractility measured by surface electromyography and by digital palpation. Both methods can be used to validate data in research and clinical setting.

Effect of trunk extensor fatigue on the postural balance of elderly and young adults during unipodal task.

Muscle fatigue can influence the various mechanisms that regulate balance. Few studies have investigated the effects of trunk extensor muscle fatigue on postural control. The purpose of this study was to evaluate the impact of trunk extensor fatigue during a one-leg balance test in young and elderly adults, as well as to determine the time necessary to recover posture control after fatigue. A total of 36 subjects (18 elderly and 18 young adults) participated in the study. Subjects were tested on a force platform to assess the postural control parameters associated with center of pressure (COP) movements, before and after a fatiguing trunk extension-flexion exercise on a roman chair carried out to exhaustion. Post-fatigue effects and postural control recovery were investigated at different times in minutes (MIN): immediately post-fatigue (postIME), after 5 (rec5MIN), 10 (rec10MIN), and 20 min (rec20MIN). Elderly subjects had greater sway (P < 0.05) than young adults in all COP parameters. In both groups, there was an increase in postIME sway compared with pre-fatigue values for all COP parameters. However, the differences were significant only for the COP velocity parameter, with more pronounced effects in young adults that did not return to pre-fatigue values at the end of rec20MIN. The present study demonstrated a significant effect of trunk extensor muscle fatigue on postural control, which was more evident in young adults than in the elderly.

Reproducibility of dynamometers in handrail format in evaluating handgrip strength and traction in young and older adults.

BACKGROUND: The aim of the present study was twofold: (1) to assess the reproducibility of two dynamometers in handrail format to measure handgrip strength and traction force in the young and older adults; (2) to compare the handgrip strength and traction of these two populations. APPROACH: Twenty-four volunteers (12 older adults and 12 young adults) performed a functional effort related to handgrip strength and traction force during stair climbing. The participants were evaluated two times (separated by one week) using a coupled dynamometer that quantifies the muscular effort in grip and traction simultaneously to simulate stair climbing in bus service. RESULTS: The young adults performed significantly better (p < 0.04) than the older adults in both handgrip and traction efforts (medium to large effect size), with excellent reliability (Intraclass Coefficient Correlation > 0.9) and low error of measure. The dynamometers were able to discriminate the two population groups (sensitive validity) and showed excellent reproducibility estimates for handgrip and traction strength in both young and older adults. CONCLUSION: These instruments could be useful in assessing handgrip and traction strength needed to climb stairs, especially for the older adults, who normally have more difficulty performing this task.

Association between Concentric and Eccentric Isokinetic Torque and Unilateral Countermovement Jump Variables in Professional Soccer Players.

Isokinetic tests have been highly valuable to athletic analysis, but their cost and technical operation turn them inaccessible. The purpose of this study was to verify the correlation between unilateral countermovement jump variables and isokinetic data. Thirty-two male professional soccer players were subjected to the isokinetic testing of both knee extensors and flexors in concentric and eccentric muscle contractions. They also executed unilateral countermovement vertical jumps (UCMJ) to compare maximum height, ground reaction force, and impulse power with isokinetic peak torque. Data analysis was conducted through Pearson correlation and linear regression. A high correlation was found between dominant unilateral extensor concentric peak torque and the UCMJ maximum height of the dominant leg. The non-dominant leg jump showed a moderate correlation. No other variable showed statistical significance. Linear regression allowed the generation of two formulae to estimate the peak torque from UCMJ for dominant and non-dominant legs. Although few studies were found to compare our results, leading to more studies being needed, a better understanding of the unilateral countermovement jump may be used in the future as a substitute to the expensive and technically demanding isokinetic testing when it is unavailable, allowing the assessment of lower limb physical asymmetries in athletic or rehabilitation environments.

Strength Level of Professional Elite Soccer Players after the COVID-19 Lockdown Period: A Retrospective Double-Arm Cohort Study.

BACKGROUND: It is well known that periods of inactivity generate a loss of muscle strength, a fundamental component of sports performance in soccer. However, little information is available on the decrease in strength levels in professional soccer players after the quarantine lockdown that occurred during the COVID-19 pandemic. AIM: To compare the isokinetic peak torque profiles of professional soccer players from different teams before and after the quarantine period generated by COVID-19. METHODS: A retrospective observational study was performed using data collected from two different professional elite-level soccer teams just before and immediately after the COVID-19 quarantine period. One team gave individual instructions to its players for conditioning maintenance at home during the quarantine period, while the other team used regular video calls to maintain the player's conditioning status on home training. The main outcomes were the mean peak torque of knee extensors and flexors, from concentric and eccentric contractions of each playing position. Analysis. A two-way ANOVA analysis was used to compare peak torque before and after the quarantine period and between both teams' strategies, showing a statistically significant reduction in eccentric knee flexor peak torque from the team that did not have remote monitoring. CONCLUSIONS: Remote monitoring programs are recommended so that athletes are less affected by the deleterious effects of confinement.

Is pilates better than other exercises at increasing muscle strength? A systematic review.

Our objective was to verify the effectiveness of Pilates method compared against other exercise modalities for muscle strength increase, balance and flexibility. Method: Databases used and its respective results were: CENTRAL (n = 456), CINAHL (n = 291), EMBASE (n = 313), PEDro (n = 176), PUBMED (n = 236), SCIELO (n = 98), SPORTDiscus (n = 197) e Web of Science (n = 150). It included randomized controlled studies using Pilates and others exercise modalities that measured muscle strength. Results: Eleven studies were included for analysis. The mean methodological quality score of these studies, evaluated by the PEDro scale, was 6 ± 1. For the primary outcome, not being observed this difference for dynamic force (SMD = -0.29; 95%IC -0.69; 0.10), isometric (SMD = 0.20; 95%IC -0.06; 0.47) or resistance (SMD = -0.19; 95%IC -0.46; 0.07). For secondary outcomes, there was no difference for balance and flexibility. Conclusion: In conclusion, there is very low to low evidence that there is no difference between Pilates and other exercise modalities for dynamic strength, isometric strength, resistance strength, balance and flexibility.