Effect of a home-based resistance exercise program in elderly participants with osteoporosis: a randomized controlled trial.

The effectiveness of home-based resistance exercise in elder participants with osteoporosis remains unclear. This study demonstrates the beneficial effects of this mode of exercise on improving physical function, increasing confidence in exercise, and reducing fear of falling. INTRODUCTION: This study aims to evaluate the effect of a home-based resistance exercise (HBRE) program versus control on physical function, exercise self-efficacy, falling efficacy, and health-related quality of life (HRQOL). METHODS: This randomized controlled trial included 72 elderly participants with osteoporosis. Participants in the intervention group received a 12-week HBRE program, and the control group received usual care. The primary outcome was physical function, including muscle strength and balance ability; secondary outcomes were exercise self-efficacy, falling efficacy, and HRQOL. Within-group and between-group changes in outcome were evaluated by t-test and rank-sum test. RESULTS: A total of 68 subjects were included in the final analysis. Improvement in physical function was significantly greater in the HBRE group compared with controls. On a psychological level, exercise self-efficacy and falling efficacy improved significantly in the HBRE group; no significant change was observed in the control group. Most of the dimensions of HRQOL demonstrated improvements as well. The adherence was 85.29%, with no adverse events related to the exercise. CONCLUSION: A 12-week HBRE program was safe non-pharmacological therapy for elderly participants with osteoporosis, improving physical function, exercise self-efficacy, reduced fear of falling, and improved HRQOL. TRIAL REGISTRATION: Chinese Clinical Trial Register: ChiCTR2100051455. Registered 23.09.21. Retrospectively registered.

Attention to principles of exercise training: an updated systematic review of randomized controlled trials in cancers other than breast and prostate.

BACKGROUND: The primary objective of this systematic review was to update our previous review on randomized controlled trials (RCTs) of exercise in cancers other than breast or prostate, evaluating: 1) the application of principles of exercise training within the exercise prescription; 2) reporting of the exercise prescription components (i.e., frequency, intensity, time, and type (FITT)); and 3) reporting of participant adherence to FITT. A secondary objective was to examine whether reporting of these interventions had improved over time. METHODS: MEDLINE, EMBASE, CINAHL and SPORTDiscus databases were searched from 2012 to 2020. Eligible studies were RCTs of at least 4 weeks of aerobic and/or resistance exercise that reported on physiological outcomes relating to exercise (e.g., aerobic capacity, muscular strength) in people with cancer other than breast or prostate. RESULTS: Eighty-six new studies were identified in the updated search, for a total of 107 studies included in this review. The principle of specificity was applied by 91%, progression by 32%, overload by 46%, initial values by 72%, reversibility by 7% and diminishing returns by 5%. A significant increase in the percentage of studies that appropriately reported initial values (46 to 80%, p < 0.001) and progression (15 to 37%, p = 0.039) was found for studies published after 2011 compared to older studies. All four FITT prescription components were fully reported in the methods in 58% of all studies, which was higher than the proportion that fully reported adherence to the FITT prescription components in the results (7% of studies). Reporting of the FITT exercise prescription components and FITT adherence did not improve in studies published after 2011 compared to older studies. CONCLUSION: Full reporting of exercise prescription and adherence still needs improvement within exercise oncology RCTs. Some aspects of exercise intervention reporting have improved since 2011, including the reporting of the principles of progression and initial values. Enhancing the reporting of exercise prescriptions, particularly FITT adherence, may provide better context for interpreting study results and improve research to practice translation.

Strength and Conditioning Practices of Head Coaches of Male and Female Interscholastic Sport Teams.

Shurley, JP, Ednie, AJ, and Rudebeck, TJ. Strength and conditioning practices of head coaches of male and female interscholastic sport teams. J Strength Cond Res 34(7): 1894-1902, 2020-In a 1989 position paper, the National Strength and Conditioning Association (NSCA) recommended that male and female athletes be trained in a similar manner with regard to modalities and program design. To determine whether that recommendation is being followed, this study examined training practices of coaches of male and female athletes at the interscholastic level. Electronic surveys regarding strength training practices were distributed to head coaches of boys' football, basketball, soccer, and baseball and girls' volleyball, basketball, soccer, and softball in the states of Texas and Wisconsin. Overall, 85% of coaches (n = 85) reported that they require their athletes to strength train. There was no difference in whether strength training was required based on athlete sex (X = 0.16, df = 1, p = 0.69) or the sex of the coach (X = 0.63, df = 1, p = 0.43). The majority (67%) of teams strength trained once weekly during the season and 21% trained twice weekly. In the off-season, only 12% of teams trained once weekly, whereas 44% of teams strength trained 2 times per week and 29% 3 times weekly. The most common types of lift performed for both sexes were "bodyweight exercises," followed by "dumbbell presses," bench press, back squats, and front squats. Both female and male athletes trained most commonly at 4-8 repetition and 9-12 repetition ranges. In contrast to previous studies and in accordance with the NSCA recommendation, it seems that the high school coaches surveyed in this work largely train male and female athletes in a similar fashion with regard to training frequency, intensity, and modalities.

Effects of 12 Weeks of Resistance Training on Cardiovascular Risk Factors in School Adolescents.

Background and objectives: The practice of physical exercise, especially resistance exercise, is important for the treatment and/or prevention of cardiovascular risk factors in adult individuals. However, there are few studies on its effects on adolescent individuals. Therefore, the aim of the present study was to evaluate the effects of applying a 12-week resistance training program on cardiovascular risk factors in adolescents. Materials and Methods: Thus, 122 adolescents aged 13-16 years of both genders participated in the study from school in the city of Lagarto, Sergipe (SE), Brazil, divided into two groups: Control Group (CG) and Group undergoing resistance training (RTG). Blood collection and anthropometric measurements were performed before and after the 12-week resistance training program (RTP). Results: After 12 weeks of the RTP in the adolescents, there was a reduction in the triglyceride variables (9.55%, p = 0.0286), Low-Density Lipoproteins (LDL) (5.42%, p = 0.0244), non-High-Density Lipoproteins (HDL) (5.40%, p = 0.0019), blood glucose (6.71%, p = 0.0040), systolic blood pressure (10.13%, p < 0.0001), as well as an increase in the body weight variable (1.73%, p = 0.0003). Conclusions: It was concluded that a 12-week RTP can prevent and/or alleviate the development of several chronic degenerative diseases in adulthood and that resistance training is important for maintaining the health of adolescents.

Adjusting Assistance Commensurates with Patient Effort During Robot-Assisted Upper Limb Training for a Patient with Spasticity After Cervical Spinal Cord Injury: A Case Report.

Limited evidence is available on optimal patient effort and degree of assistance to achieve preferable changes during robot-assisted training (RAT) for spinal cord injury (SCI) patients with spasticity. To investigate the relationship between patient effort and robotic assistance, we performed training using an electromyography-based robotic assistance device (HAL-SJ) in an SCI patient at multiple settings adjusted to patient effort. In this exploratory study, we report immediate change in muscle contraction patterns, patient effort, and spasticity in a 64-year-old man, diagnosed with cervical SCI and with American Spinal Injury Association Impairment Scale C level and C4 neurological level, who underwent RAT using HAL-SJ from post-injury day 403. Three patient effort conditions (comfortable, somewhat hard, and no-effort) by adjusting HAL-SJ's assists were set for each training session. Degree of effort during flexion and extension exercise was assessed by visual analog scale, muscle contraction pattern by electromyography, modified Ashworth scale, and maximum elbow extension and flexion torques, immediately before and after each training session, without HAL-SJ. The amount of effort during training with the HAL-SJ at each session was evaluated. The degree of effort during training can be set to three effort conditions as we intended by adjusting HAL-SJ. In sessions other than the no-effort setting, spasticity improved, and the level of effort was reduced immediately after training. Spasticity did not decrease in the training session using HAL-SJ with the no-effort setting, but co-contraction further increased during extension after training. Extension torque was unchanged in all sessions, and flexion torque decreased in all sessions. When performing upper-limb training with HAL-SJ in this SCI patient, the level of assistance with some effort may reduce spasticity and too strong assistance may increase co-contraction. Sometimes, a patient's effort may be seemingly unmeasurable; hence, the degree of patient effort should be further measured.

Effect of a Combined Stretching and Strength Training Program on Gait Function in Children with Cerebral Palsy, GMFCS Level I & II: A Randomized Controlled Trial.

Background and objectives: Ambulant children with cerebral palsy (CP) often develop impaired gait, and reduced active knee extension is often a part of the problem. This study aimed to evaluate the effect of a combined intervention program including stretching and progressive resistance exercise (PRE) targeting active knee extension on gait function, in children with spastic CP. Materials and methods: Thirty-seven children (21 boys, 16 girls, mean age 10.2 (±2.3) years), classified by Gross Motor Function Classification System I-III, were randomized to an intervention (n = 17) and a comparison group (n = 20). The intervention group received a 16-week combined exercise program (3 sessions per week) including stretching of hamstrings and PRE targeting the lower extremities, followed by a 16-week maintenance program (1 session per week). The comparison group received care as usual. Gait function was evaluated by three-dimensional gait analysis (3DGA); knee, hip and pelvic kinematics in the sagittal plane, step length and speed, Gait Deviation Index (GDI), and Six-Minute Walk test (6MWT) at 0, 16, and 32 weeks. Results: There were no statistically significant differences between the intervention group and the comparison group for any of the gait parameters measured at 16 and 32 weeks. There was a significant increase in gait distance measured by 6MWT within both groups; however, no differences between the groups were found. Conclusion: A 16-week combined stretching and PRE program followed by a 16-week maintenance program did not improve gait function in ambulant children with CP.

Do Trials of Resistance Training to Improve Mobility After Stroke Adhere to the American College of Sports Medicine Guidelines? A Systematic Review.

OBJECTIVE: To determine whether resistance training to improve mobility outcomes after stroke adheres to the American College of Sports Medicine (ACSM) guidelines, and whether adherence was associated with better outcomes. DATA SOURCES: Online databases searched from 1975 to October 30, 2016. STUDY SELECTION: Randomized controlled trials examining the effectiveness of lower limb strength training on mobility outcomes in adult participants with stroke. DATA EXTRACTION: Two independent reviewers completed data extraction. Quality of trials was determined using the Cochrane Risk of Bias Tool. Trials were scored based on their protocol's adherence to 8 ACSM recommendations. To determine if a relation existed between total adherence score and effect size, Spearman ρ was calculated, and between individual recommendations and effect size, Mann-Whitney U or Kruskal-Wallis tests were used. DATA SYNTHESIS: Thirty-nine trials met the inclusion criteria, and 34 were scored on their adherence to the guidelines. Adherence was high for frequency of training (100% of studies), but few trials adhered to the guidelines for intensity (32%), specificity (24%), and training pattern (3%). Based on the small number of studies that could be included in pooled analysis (n=12), there was no relation between overall adherence and effect size (Spearman ρ=-.39, P=.21). CONCLUSIONS: Adherence to the ACSM guidelines for resistance training after stroke varied widely. Future trials should ensure strength training protocols adhere more closely to the guidelines, to ensure their effectiveness in stroke can be accurately determined.

Long-term evaluation of the implementation of a large fall and fracture prevention program in long-term care facilities.

BACKGROUND: Falls and fractures are extremely frequent in long-term care facilities (LTCFs). Therefore, a fall and fracture prevention program was started in nearly 1000 LTCFs in Bavaria/Germany between 2007 and 2010. The components of the program were exercise classes, the documentation of falls, environmental adaptations, medication reviews, the recommendation to use hip protectors and education of staff. The present study aimed to provide a comprehensive evaluation of the implementation process of the program regarding results of the implementation phase and the follow-up of 3-9 years after start of implementation. METHODS: Data from numerous sources were used, including data from published studies, statistical data, health insurance claims data and unpublished data from an online questionnaire. To incorporate different aspects, time periods and results, the RE-AIM framework was applied. RESULTS: The program was adopted by 942 of the 1150 eligible LTCFs and reached about 62,000 residents. During the implementation phase exercise classes and recommendation about environmental adaptations were offered in nearly all LTCFs. 13.5% of the residents participated in exercise classes. Hip protectors were available for 9.2% of all residents. In the first implementation wave, femoral fracture rate was significantly reduced by 18% in the first year. At follow-up nearly 90% of all LTCFs still offered exercise classes, which were attended by about 11% of residents. However, only 10% of the exercise classes completely fulfilled the requirements of an effective strength and balance training. Individual advice about environmental adaptations was provided in 74.3% of the LTCFs and nearly all LTCFs claimed to offer hip protectors to their residents. A long-term effect of the program on femoral fractures could not be detected. CONCLUSIONS: The program did not affect the femoral fracture rate in the long run. Possible reasons could be a high turn-over of the staff, a reduced fidelity of training components or a shift in daily priorities among the staff.

Strength Training to Enhance Early Recovery after Hematopoietic Stem Cell Transplantation.

Intensive cancer treatment followed by hematopoietic stem cell transplantation (HCT) results in moderate to severe fatigue and physical inactivity, leading to diminished functional ability. The purpose of this study was to determine the efficacy of an exercise intervention, strength training to enhance early recovery (STEER), on physical activity, fatigue, muscle strength, functional ability, and quality of life after HCT. This single-blind, randomized clinical trial compared strength training (n = 33) to usual care plus attention control with health education (UC + AC with HE) (n = 34). Subjects were stratified by type of transplantation and age. STEER consisted of a comprehensive program of progressive resistance introduced during hospitalization and continued for 6 weeks after hospital discharge. Fatigue, physical activity, muscle strength, functional ability, and quality of life were assessed before HCT hospital admission and after intervention completion. Data were analyzed using split-plot analysis of variance. Significant time × group interactions effects were noted for fatigue (P = .04). The STEER group reported improvement in fatigue from baseline to after intervention whereas the UC + AC with HE group reported worsened fatigue from baseline to after intervention. Time (P < .001) and group effects (P = .05) were observed for physical activity. Physical activity declined from baseline to 6 weeks after hospitalization. The STEER group was more physically active. Functional ability tests (timed stair climb and timed up and go) resulted in a significant interaction effect (P = .03 and P = .05, respectively). Subjects in the UC + AC with HE group were significantly slower on both tests baseline to after intervention, whereas the STEER group's time remained stable. The STEER group completed both tests faster than the UC + AC with HE group after intervention. Study findings support the use of STEER after intensive cancer treatment and HCT. Strength training demonstrated positive effects on fatigue, physical activity, muscle strength, and functional ability. The exact recovery patterns between groups and over time varied; the STEER group either improved or maintained their status from baseline to after intervention (6 weeks after hospital discharge) whereas the health education group generally declined over time or did not change.

Clarity in reporting terminology and definitions of set endpoints in resistance training.

Previous resistance training (RT) recommendations and position stands have addressed variables that can be manipulated when producing RT interventions. However, 1 variable that has received little discussion is set endpoints (i.e., the endpoint of a set of repetitions). Set endpoints in RT are often considered to be proximity to momentary failure and are thought to be a primary variable determining effort in RT. Further, there has been ambiguity in the use and definition of terminology that has created issues in interpretation of research findings. The purpose of this paper was to: (1) provide an overview of the ambiguity in historical terminology around set endpoints; (2) propose a clearer set of definitions related to set endpoints; and (3) highlight the issues created by poor terminology and definitions. It is hoped this may permit greater clarity in reporting, interpretation, and application of RT interventions for researchers and practitioners. Muscle Nerve 56: 368-374, 2017.

The Ottawa panel clinical practice guidelines for the management of knee osteoarthritis. Part two: strengthening exercise programs.

OBJECTIVE: To identify effective strengthening exercise programs and provide rehabilitation teams and patients with updated, high-quality recommendations concerning traditional land-based exercises for knee osteoarthritis. METHODS: A systematic search and adapted selection criteria included comparative controlled trials with strengthening exercise programs for patients with knee osteoarthritis. A panel of experts reached consensus on the recommendations using a Delphi survey. A hierarchical alphabetical grading system (A, B, C+, C, D, D+ or D-) was based on statistical significance ( p < 0.5) and clinical importance (⩾15% improvement). RESULTS: The 26 high-quality studies identified demonstrated that various strengthening exercise programs with/without other types of therapeutic exercises are generally effective for improving knee osteoarthritis management within a six-month period. Strengthening exercise programs demonstrated a significant improvement for pain relief (four Grade A, ten Grade B, two Grade C+), physical function (four Grade A, eight Grade B) and quality of life (three Grade B). Strengthening in combination with other types of exercises (coordination, balance, functional) showed a significant improvement in pain relief (three Grade A, 11 Grade B, eight Grade C+), physical function (two Grade A, four Grade B, three Grade C+) and quality of life (one Grade A, one Grade C+). CONCLUSION: There are a variety of choices for strengthening exercise programs with positive recommendations for healthcare professionals and knee osteoarthritis patients. There is a need to develop combined behavioral and muscle-strengthening strategies to improve long-term maintenance of regular strengthening exercise programs.

Exercise recommendations for patients with type 2 diabetes.

The American College of Sports Medicine and American Diabetes Association recommend that patients with type 2 diabetes participate in at least 150 minutes of moderate exercise weekly with resistance training two or three times weekly. This article reviews the guidelines, preparticipation cardiovascular screening recommendations, and considerations for patients with diabetes and comorbidities who are planning to participate in regular exercise regimens.

Correlates of resistance training in post-treatment breast cancer survivors.

PURPOSE: To explore demographic, health, social-cognitive and behavioural correlates of resistance training among post-treatment breast cancer survivors. METHODS: A sample of 330 post-treatment breast cancer survivors recruited from across Australia completed a mailed questionnaire. A multivariate logistical regression model was used to test associations between independent variables and meeting the resistance training guidelines. RESULTS: Less than a quarter of the participants were meeting the resistance training guidelines of at least two sessions of resistance training per week. Higher task self-efficacy for resistance training (p < 0.01) and greater goal-setting behaviour (p < 0.05) were identified as significant predictors of meeting the resistance training guidelines, with a one unit increase in task self-efficacy and goal setting, increasing the odds of meeting the resistance training guidelines by a factor of approximately 1.2 (odds ratio (OR) task self-efficacy = 1.23, 95 % confidence interval (CI) = 1.05-1.43; goal-setting OR = 1.20, 95 % CI = 1.04-1.38). No other variables significantly predicted meeting the resistance training guidelines in the multivariate analysis. CONCLUSIONS: Strategies targeting task self-efficacy and goal-setting behaviours are likely to be important intervention components in resistance training interventions for breast cancer survivors. IMPLICATIONS FOR CANCER SURVIVORS: The findings of this study will be useful for informing the development of evidence-based interventions aiming to promote resistance training among this group.

The effect of horse simulator riding on visual analogue scale, body composition and trunk strength in the patients with chronic low back pain.

BACKGROUND: Chronic low back pain (CLBP) is one of the most common musculoskeletal disorders, and thus effective treatments are required. Recently, real horseback riding has been reported to be beneficial for the patients. However, it has some limitations, such as limited approaches and safety issues. OBJECTIVE: The purpose of this study was to investigate the effect of horse simulator riding on back pain, body composition and trunk strength in the patients with CLBP. PARTICIPANTS: Forty-seven men with CLBP (mean age 20.55 ± 1.38 years) were randomly divided into a control group (n = 23) and a horse simulator riding group (n = 24), and visual analogue scale (VAS), body composition and isokinetic trunk strength were measured after 8 weeks for which subjects in a horse simulator riding group had performed the horse simulator exercise (HSE). RESULTS: Horse simulator exercise significantly reduced pain scores of VAS and enhanced isokinetic torques of trunk at 30 and 90°/s. There were also significantly increased muscle mass and decreased fat mass in horse simulator riding group. CONCLUSION: It can be inferred that HSE may be helpful in relief of back pain and recovery of back function through developing trunk strength and balancing the ratio of trunk flexor/extensor muscles.

What does standard rehabilitation practice after total hip replacement in the UK entail? Results of a mixed methods study.

BACKGROUND: There is evidence of prolonged poor function in patients following total hip replacement (THR). Studies of progressive resistance training (PRT) interventions to improve function are often compared to 'standard' practice which is not well defined. This study aimed to investigate 'standard' rehabilitation care in the UK after total hip replacement (THR) as well as determine whether PRT was part of 'standard' care. METHODS: After ethical approval, questionnaire item development about rehabilitation practice was guided by a focus group interview (after informed consent) with physiotherapists (n = 4; >5 years post-qualification) who regularly treated THR patients. An online questionnaire investigating the exercises prescribed and rehabilitation practice following THR was developed and sent to physiotherapists working in hospitals in the UK. The survey was performed from January to May 2011. The survey results were analysed (frequency (%) of responses) focusing on the exercises the physiotherapists considered important, as well as their use of PRT in prescribed regimes. RESULTS: 106 responses were obtained from physiotherapists in the UK. The survey respondents considered that the most important muscles to target in all phases of rehabilitation were the hip abductors (62.2%), followed by the quadriceps (16.9%), and other muscles (21%). Exercise type prescribed revealed no consensus, with weight bearing (42%), functional (45%) and Bed-based/Bridging/Postural exercises (13%) favoured. 83.7% were able to define the basis of progressive resistance training (PRT), but only 33% prescribed it. CONCLUSIONS: Standard physiotherapy rehabilitation in the UK after THR is variable, and appears to rarely include PRT. This may be a factor in prolonged poor function in some patients after this common operation.

Towards standardization of the nomenclature of resistance training exercises.

There is a disagreement surrounding the names of resistance training exercises. The purpose of this study was to survey different professionals regarding the nomenclature of resistance training exercises. Two hundred five participants volunteered for the study, of which, 64.9 % were male. Participants self-identified as either certified athletic trainer (22.4%), academic (18.5%), strength and conditioning coach (25.9%), personal trainer (15.6%), or clinician (17.6%). Participants were asked to name 10 resistance training exercises as depicted by pictures. A χ2 for exercise name by current profession analysis was used to analyze frequency differences. All exercises in the survey yielded inconsistent terminology primarily related to the responders' profession and 3 items in their naming patterns as follows: specification, equipment, and exercise. These results reveal a need to establish consistent naming pattern guidelines for resistance training exercises. The use of a consistent naming pattern may provide direction and clarity when working with athletes and clients in a strength training environment. We suggest a "specification, equipment, exercise" (e.g., 1 arm dumbbell row) naming pattern be used when naming resistance training exercises.

CSCS certification and school enrollment impacts upon high school strength facilities, equipment, and safety.

The rapid growth and expanding use of high school strength and conditioning facilities (SCFs) creates a need to research and better understand these vital facilities. This study was designed to examine SCFs at the high school level including facility size, equipment, leadership/staffing, and safety. A 70-item online survey instrument, developed with expert input from certified strength professionals, was used to collect data regarding the SCFs in high schools throughout a midwestern state, and was distributed via email to a total of 390 high school athletic directors. Survey respondents (n = 108) all reported the presence of SCFs with 95.4% indicating a dedicated SCF space. A strong positive correlation (r = 0.610, p ≤ 0.001) was determined between the variables of SCF size in square feet and school size measured by total enrollment. Analysis of variance and χ² analyses revealed significant differences in equipment, facility size, and safety factors based on the categorical variables of school size and the presence of certified strength and conditioning specialist (CSCS) leadership. It appears the CSCS's application of their scientific knowledge goes beyond training athletes for the goal of improving athletic performance to actually influence the SCF itself. Athletic administrators at the high school level need to recognize the impact CSCS program leadership can have on the overall quality of the strength and conditioning program and facility.

Electromyographic normalization procedures for determining exercise intensity of closed chain exercises for strengthening the quadriceps femoris muscles.

The purpose of this study was to compare the electromyographic (EMG) amplitudes of the quadriceps femoris (QF) muscles during a maximum voluntary isometric contraction (MVIC) to submaximal and maximal dynamic concentric contractions during active exercises. A secondary purpose was to provide information about the type of contraction that may be most appropriate for normalization of EMG data if one wants to determine if a lower extremity closed chain exercise is of sufficient intensity to produce a strengthening response for the QF muscles. Sixty-eight young healthy volunteers (39 female, 29 male) with no lower extremity pain or injury participated in the study. Surface electrodes recorded EMG amplitudes from the vastus medialis obliquus (VMO), rectus femoris (RF), and vastus lateralis (VL) muscles during 5 different isometric and dynamic concentric exercises. The last 27 subjects performed an additional 4 exercises from which a second data set could be analyzed. Maximum isokinetic knee extension and moderate to maximum closed chain exercises activated the QF significantly more than a MVIC. A 40-cm. lateral step-up exercise produced EMG amplitudes of the QF muscles of similar magnitude as the maximum isokinetic knee extension exercises and would be an exercise that could be considered for strengthening the QF muscles. Most published EMG studies of exercises for the QF have been performed by comparing EMG amplitudes during dynamic exercises to a MVIC. This procedure can lead one to overestimate the value of a dynamic exercise for strengthening the QF muscles. We suggest that when studying the efficacy of a dynamic closed chain exercise for strengthening the QF muscles, the exercise be normalized to a dynamic maximum muscle contraction such as that obtained with knee extension during isokinetic testing.

Optimum loading for maximizing muscle power output: the effect of training history.

Although the effect of external load on the mechanical output of individual muscle has been well documented, the literature still provides conflicting evidence regarding whether the optimum loading (L(opt)) for exerting the maximum muscle power output (MPO) could be different for individuals with different levels of strength and power. The aim of this study was to explore the effect of training history on L(opt) that maximizes MPO during the 6-s maximal cycling sprint test. Forty healthy young males (strength-and speed-trained athletes, and physically active and sedentary non-athletes) were tested on maximum strength, and on peak MPO when loaded 5-12% of body weight (BW). As expected, the strength trained and sedentary participants, respectively, revealed the highest and lowest strengths and MPO (p < 0.001). However, the main finding was a significant across-group difference in L(opt) (p < 0.001) revealing the values 9.7% (for strength trained), 9.2% (speed trained), 8.7% (active), and 8.0% of BW (sedentary individuals). This suggests that the effects of external loading on maximum MPO in complex functional movements could be training history dependent. In addition to revealing a sensitivity of the 6-s maximal cycling sprint tests (and, perhaps, other maximum cycling tests), the results suggest that the external loading in routine MPO tests should not be solely adjusted to a fixed percentage of subject's BW (as routinely done in standard tests), but also to their training history. The same phenomenon remains to be evaluated in a number of other routine tests of MPO and other maximum performance tasks.

Algorithmic extraction of smartphone accelerometer-derived mechano-biological descriptors of resistance exercise is robust to changes in intensity and velocity.

BACKGROUND: It was shown that single repetition, contraction-phase specific and total time-under-tension (TUT) can be extracted reliably and validly from smartphone accelerometer-derived data of resistance exercise machines using user-determined resistance exercise velocities at 60% one repetition maximum (1-RM). However, it remained unclear how robust the extraction of these mechano-biological descriptors is over a wide range of movement velocities (slow- versus fast-movement velocity) and intensities (30% 1-RM versus 80% 1-RM) that reflect the interindividual variability during resistance exercise. OBJECTIVE: In this work, we examined whether the manipulation of velocity or intensity would disrupt an algorithmic extraction of single repetitions, contraction-phase specific and total TUT. METHODS: Twenty-seven participants performed four sets of three repetitions of their 30% and 80% 1-RM with velocities of 1 s, 2 s, 6 s and 8 s per repetition, respectively. An algorithm extracted the number of repetitions, single repetition, contraction-phase specific and total TUT. All exercises were video-recorded. The video recordings served as the gold standard to which algorithmically-derived TUT was compared. The agreement between the methods was examined using Limits of Agreement (LoA). The Pearson correlation coefficients were used to calculate the association, and the intraclass correlation coefficient (ICC 2.1) examined the interrater reliability. RESULTS: The calculated error rate for the algorithmic detection of the number of single repetitions derived from two smartphones accelerometers was 1.9%. The comparison between algorithmically-derived, contraction-phase specific TUT against video, revealed a high degree of correlation (r > 0.94) for both exercise machines. The agreement between the two methods was high on both exercise machines, intensities and velocities and was as follows: LoA ranged from -0.21 to 0.22 seconds for single repetition TUT (2.57% of mean TUT), from -0.24 to 0.22 seconds for concentric contraction TUT (6.25% of mean TUT), from -0.22 to 0.24 seconds for eccentric contraction TUT (5.52% of mean TUT) and from -1.97 to 1.00 seconds for total TUT (5.13% of mean TUT). Interrater reliability for single repetition, contraction-phase specific TUT was high (ICC > 0.99). CONCLUSION: Neither intensity nor velocity disrupts the proposed algorithmic data extraction approach. Therefore, smartphone accelerometers can be used to extract scientific mechano-biological descriptors of dynamic resistance exercise with intensities ranging from 30% to 80% of the 1-RM with velocities ranging from 1 s to 8 s per repetition, respectively, thus making this simple method a reliable tool for resistance exercise mechano-biological descriptors extraction.