EFFECT OF BLOOD FLOW RESTRICTION TRAINING ON MUSCULAR PERFORMANCE, PAIN AND VASCULAR FUNCTION.

BACKGROUND: Blood flow restriction (BFR) training enhances muscular strength and hypertrophy in several populations including older adults and injured athletes. However, the efficacy of emerging BFR technologies on muscular adaptations, vascular health, and pain is unclear. PURPOSE: The purpose of this study was to examine muscular performance, pain and vascular function in response to eight weeks of BFR compared to traditional resistance training and a control group. STUDY DESIGN: Randomized control trial. METHODS: Thirty-one overtly healthy participants (age: 23 ± 4y, 65% female) underwent eight weeks of supervised high load resistance training (RES), low load resistance training with BFR (BFR) or no training (control, CON). RES and BFR (with pneumatic bands) performed seven upper and lower body exercises, two to three sessions per week at 60% and 30% of one-repetition maximum (1RM), respectively. Twenty-four hours post-exercise, general muscle soreness was assessed via a visual analog scale (VAS) and present pain intensity (PPI) of the McGill Pain Questionnaire. At baseline and after eight weeks, participants underwent one-repetition maximum (1RM), and flow-mediated dilation (FMD) testing. RESULTS: At baseline all groups exhibited similar muscle strength and endurance and vascular function. At the end of training, RES and BFR groups significantly increased muscle strength (1RM) to a similar magnitude as compared to the CON group (p < 0.0001), but did not alter body composition. FMD significantly increased in RES and BFR groups compared to CON group (p = 0.006). VAS and PPI were similar between RES and BFR groups throughout the exercise sessions until VAS decreased in the BFR group after the last session compared to the RES group (p = 0.02). CONCLUSION: Compared to RES, BFR resulted in similar muscular performance (strength and endurance) and vascular improvements at a lower exercise intensity, suggesting BFR is an effective alternative to high load resistance training. Further longitudinal studies may gain greater understanding regarding general muscle pain and soreness when using BFR. LEVEL OF EVIDENCE: Therapy, Level 2.

Combined Effects of Self-Myofascial Release and Dynamic Stretching on Range of Motion, Jump, Sprint, and Agility Performance.

Richman, ED, Tyo, BM, and Nicks, CR. Combined effects of self-myofascial release and dynamic stretching on range of motion, jump, sprint, and agility performance. J Strength Cond Res 33(7): 1795-1803, 2019-Massage has been used as both a pre- and post-exercise modality with purported benefits to flexibility and athletic performance. This study was designed to determine the effect of a 6-minute protocol of self massage known as self-myofascial release (SMR) using a foam rolling device in conjunction with a general warm-up and sport-specific dynamic stretching (DS) session on flexibility and explosive athletic performance in a sample of 14 female collegiate athletes. After familiarization, participants completed 2 testing sessions that began with 5 minutes of jogging at a self-selected pace, followed by either a 6-minute foam rolling session (SMR) or 6 minutes of light walking (LW) and a subsequent 6-minute period of sport-specific DS. Sit-and-reach (SR) was measured after a general warm-up, the SMR, or LW session, and following DS, after which participants performed 3 trials each of squat jump (SJ), countermovement jump (CMJ), and drop jump (DJ). Two additional tests, the agility T-Test (TT) and a 10-yd short sprint (SP), were then performed. The change in SR after SMR was significantly greater than the change seen in SR after LW, although the total changes seen in each condition were not statistically different after the addition of DS. Squat jump and CMJ improved by 1.72 ± 2.47 cm and 2.63 ± 3.74 cm (p = 0.070, p = 0.070), with no significant change to DJ, SP, and TT. Self-myofascial release in the form of foam rolling after a general warm-up and preceding a DS session seems to improve SJ and CMJ with no detriment to flexibility, DJ, sprint, and agility performance in comparison with LW and DS.

Evaluation of Seasonal Changes in Fitness, Anthropometrics, and Body Composition in Collegiate Division II Female Soccer Players.

Peart, AN, Nicks, CR, Mangum, M, and Tyo, BM. Evaluation of seasonal changes in fitness, anthropometrics, and body composition in collegiate division II female soccer players. J Strength Cond Res 32(7): 2010-2017, 2018-The purpose of this study was to investigate anthropometrics, body composition, aerobic and anaerobic fitness of collegiate Division II female soccer players throughout a calendar year. Eighteen (20 ± 0.9 years) National Collegiate Athletics Association division II female soccer players from the same team participated in the study. Anthropometrics and body composition variables were assessed in addition to the counter movement jump (CMJ), Wingate Anaerobic Test (WAT), and peak oxygen uptake (V[Combining Dot Above]O2peak). Data were collected over 5 time points: end of competitive seasons (ECS1 and ECS2), beginning of off-season (BOS), end of off-season (EOS), and preseason (PS). Repeated-measures analysis of variance was conducted to compare test scores among all 5 data collection points. Where appropriate, Bonferroni post hoc tests were used to determine which points were significantly different. Hip circumference decreased significantly (p < 0.001) from EOS (98.47 ± 6.5 cm) to PS (94.46 ± 6.8 cm). Fat mass (12.73 ± 5.4 kg) was significantly different in ECS2 compared with BOS and EOS means (p ≤ 0.05) and percentage of body fat (%BF) (20.08 ± 5.44) significantly different in ECS2 compared with ECS1, BOS, and EOS means (p ≤ 0.05), whereas fat-free mass (FFM) was maintained from ECS1 to ECS2. Counter movement jump, WAT, and V[Combining Dot Above]O2peak performance did not significantly change from ECS1 to ECS2. Anthropometrics and body composition results are similar to previous studies measuring Division II to professional female soccer players. Counter movement jump results remained consistent and are comparable to results on Division I female soccer players. Coaches and researchers can use these data to help design and evaluate training programs throughout a calendar year.

Accelerometer-determined physical activity, mobility disability, and health.

BACKGROUND: We have a limited understanding of the objectively-determined physical activity levels among those with mobility limitations. Further, the association between objectively-measured physical activity and biomarkers among those with mobility limitations is relatively unknown. OBJECTIVE: Therefore, the primary objectives of this study were to compare accelerometer-determined physical activity levels among those with and without mobility limitations and determine if greater participation in physical activity was associated with more favorable health outcomes among those with mobility disability. METHODS: Data from the 2003-2006 NHANES were used. Mobility limitation status was self-reported; accelerometer-measured estimates of sedentary, light, and moderate-to-vigorous physical activity (MVPA) were determined; and blood samples were taken to measure various biomarkers. RESULTS: In general, adults with mobility limitations, compared to those without, engaged in more sedentary behavior and less light-intensity physical activity and MVPA. Adults with mobility limitations, had a higher BMI, waist circumference, C-reactive protein, white blood cells, neutrophil levels, triglycerides, glucose, HbA1C and homocysteine levels. If an adult were to increase their sedentary behavior by 60-min, their rate ratio for chronic disease would be expected to increase by a factor of 1.04. Similarly, for an increase of 60-min in light-intensity physical activity, the rate ratio for chronic disease would be expected to decrease by a factor of 0.95. MVPA was also significantly associated with chronic disease (RR: 0.91; 95% CI: 0.85-0.97). CONCLUSIONS: Minimizing sedentary behavior and increasing physical activity (even light-intensity) among those with mobility limitations may help to improve health outcomes.

Effect of BMI on pedometers in early adolescents under free-living conditions.

PURPOSE: Pedometers may provide valuable information regarding the ambulatory patterns of adolescents, but the effects of body mass index (BMI) on pedometer accuracy in this population are unknown.The purpose of this study was twofold: 1) to determine whether the New Lifestyles NL-2000 (NL) and the Digi-Walker SW-200 (DW) (New Lifestyles, Inc., Lees Summit, MO) yield similar step counts as compared with an ankle-mounted criterion, StepWatch 3, when worn by early adolescents in a free-living environment and 2) to study whether BMI percentile affects the accuracy of waist-mounted pedometers in adolescents. METHODS: Seventy-four early adolescents (13.0 ± 1.1 yr) wore the devices during one weekday. The study population included 33 normal weight, 21 overweight, and 20 obese participants. Two-way repeated-measures ANOVA was used to determine whether the BMI and the device were related to the number of steps per day and percentage of actual steps. RESULTS: The NL and DW recorded fewer steps than the StepWatch 3 in each BMI category (P < 0.05). In the obese group, the DW underestimated the steps more than the NL (P < 0.001). For the normal weight, overweight, and obese groups, the NL counted 89.1%, 89.1%, and 91.6% of the steps, respectively, whereas the DW counted 86.7%, 84.6%, and 72.7%, respectively. CONCLUSION: Researchers must be cognizant of the limitations of waist-mounted pedometers and carefully choose a device that suits the needs of their investigations. Because of the inaccuracies of the DW when measuring steps in obese adolescents, careful consideration must be given before choosing this device for research and interventions. The NL is a better device for assessment of adolescents' steps than the DW, especially for those who are obese.

Effects of body mass index on step count accuracy of physical activity monitors.

BACKGROUND: Activity monitors are widely used in research, and are currently being used to study physical activity (PA) trends in the US and Canada. The purpose of this study was to determine if body mass index (BMI) affects the step count accuracy of commonly used accelerometer-based activity monitors during treadmill walking. METHODS: Participants were classified into BMI categories and instructed to walk on a treadmill at 3 different speeds (40, 67, and 94 m·min(-1)) while wearing 4 accelerometer-based activity monitors (ActiGraph GT1M, ActiCal, NL-2000, and StepWatch). RESULTS: There was no significant main effect of BMI on pedometer accuracy. At the slowest speed, all waist-mounted devices significantly underestimated actual steps (P < .001), with the NL-2000 recording the greatest percentage (72%). At the intermediate speed, the ActiGraph was the least accurate, recording only 80% of actual steps. At the fastest speed, all of the activity monitors demonstrated a high level of accuracy. CONCLUSION: Our data suggest that BMI does not greatly affect the step-counting accuracy of accelerometer-based activity monitors. However, the accuracy of the ActiGraph, ActiCal, and NL-2000 decreases at slower speeds. The ankle-mounted StepWatch was the most accurate device across a wide range of walking speeds.

Validity and reliability of the Omron HJ-303 tri-axial accelerometer-based pedometer.

BACKGROUND: This study compared the validity of a new Omron HJ-303 piezoelectric pedometer and 2 other pedometers (Sportline Traq and Yamax SW200). METHODS: To examine the effect of speed, 60 subjects walked on a treadmill at 2, 3, and 4 mph. Twenty subjects also ran at 6, 7, and 8 mph. To test lifestyle activities, 60 subjects performed front-back-side-side stepping, elliptical machine and stair climbing/descending. Twenty others performed ballroom dancing. Sixty participants completed 5 100-step trials while wearing 5 different sets of the devices tested device reliability. Actual steps were determined using a hand tally counter. RESULTS: Significant differences existed among pedometers (P < .05). For walking, the Omron pedometers were the most valid. The Sportline overestimated and the Yamax underestimated steps (P < .05). Worn on the waist or in the backpack, the Omron device and Sportline were valid for running. The Omron was valid for 3 activities (elliptical machine, ascending and descending stairs). The Sportline overestimated all of these activities, and Yamax was only valid for descending stairs. The Omron andYamax were both valid and reliable in the 100-step trials. CONCLUSIONS: The Omron HJ-303, worn on the waist, appeared to be the most valid of the 3 pedometers.

Effects of body mass index and tilt angle on output of two wearable activity monitors.

UNLABELLED: Accelerometer-based activity monitors have been used to provide objective measures of physical activity and energy expenditure (EE) in free-living individuals. However, output from these devices has not been compared among normal, overweight, and obese individuals. PURPOSE: The purpose of this study was to examine the effects of body mass index (BMI) and device tilt angle on activity counts recorded by wearable monitors in a controlled laboratory setting. A secondary aim was to examine the effects of these variables on estimated EE. METHODS: Seventy-one healthy adults wore an Actical and an ActiGraph GT1M on the right and left hip, respectively, while walking at 40, 67, and 94 m·min. EE was measured by indirect calorimetry and compared with estimated values using published equations. Three-way repeated-measures ANOVA were used to examine differences in outcome variables (activity counts and EE) between speeds, BMI, and tilt angle for each device. RESULTS: No significant differences in activity counts were observed among BMI categories for either the Actical or ActiGraph (P>0.05). For the Actical, however, among those with an absolute tilt angle <10°, the obese group recorded higher activity counts than the normal weight group (P=0.01). Using the Heil two-regression model, the Actical overestimated EE by up to 35% at the intermediate speed and up to 12% at the fastest speed (P<0.001). The Freedson METs regression equation yielded closer estimates of EE than the Freedson kilocalorie regression equation. CONCLUSIONS: Our findings indicate that the Actical has limitations when comparing individuals with varying BMI and tilt angles in a controlled laboratory environment. The ActiGraph seems to be a more suitable device for making these comparisons.

Effects of body mass index and step rate on pedometer error in a free-living environment.

UNLABELLED: Pedometers could provide great insights into walking habits if they are found to be accurate for people of all weight categories. PURPOSE: the purposes of this study were to determine whether the New Lifestyles NL-2000 (NL) and the Digi-Walker SW-200 (DW) yield similar daily step counts as compared with the StepWatch 3 (SW) in a free-living environment and to determine whether pedometer error is influenced by body mass index (BMI) and speed of walking. The SW served as the criterion because of its accuracy across a range of speeds and BMI categories. Slow walking was defined as ≤80 steps per minute. METHODS: fifty-six adults (mean ± SD: age = 32.7 ± 14.5 yr) wore the devices for 7 d. There were 20 normal weight, 18 overweight, and 18 obese participants. A two-way repeated-measures ANOVA was performed to determine whether BMI and device were related to number of steps counted per day. Stepwise linear regressions were performed to determine what variables contributed to NL and DW error. RESULTS: both the NL and the DW recorded fewer steps than the SW (P < 0.001). In the normal weight and overweight groups, error was similar for the DW and NL. In the obese group, the DW underestimated steps more than the NL (P < 0.01). DW error was positively related to BMI and percentage of slow steps, whereas NL error was linearly related to percentage of slow steps. A surprising finding was that many healthy, community-dwelling adults accumulated a large percentage of steps through slow walking. CONCLUSIONS: the NL is more accurate than the DW for obese individuals, and neither pedometer is accurate for people who walk slowly. Researchers and practitioners must weigh the strengths and limitations of step counters before making an informed decision about which device to use.

Comparison of four ActiGraph accelerometers during walking and running.

UNLABELLED: Currently, researchers can use the ActiGraph 7164 or one of three different versions of the ActiGraph GT1M to objectively measure physical activity. PURPOSE: To determine whether differences exist between activity counts from the ActiGraph 7164 and the three versions of the GT1M at given walking and running speeds. METHODS: Ten male participants (23.6 +/- 2.7 yr) completed treadmill walking and running at 10 different speeds (3-min stages) while wearing the ActiGraph 7164 and the latest GT1M (GT1M-V3) or the GT1M version one (GT1M-V1) and the GT1M version two (GT1M-V2). Participants walked at 3, 5, and 7 km x h(-1) followed by running at 8, 10, 12, 14, 16, 18, and 20 km x h(-1). The accelerometers were worn on an elastic belt around the waist over the left and right sides of the hip. Testing was performed on different days using a counterbalanced within-subjects design to account for potential differences attributable to accelerometer placement. At each speed, a one-way repeated-measures ANOVA was used to examine differences between activity counts in counts per minute (cpm). Post hoc pairwise comparisons with Bonferroni adjustments were used where appropriate. RESULTS: There were no significant differences between activity counts at any given walking or running speed (P < 0.05). At all running speeds, activity counts from the ActiGraph 7164 and GT1M-V2 displayed the lowest and highest values, respectively. Output from all accelerometers peaked at 14 km x h(-1) (mean range = 8974 +/- 677 to 9412 +/- 982 cpm) and then gradually declined at higher speeds. The mean difference score at peak output between the ActiGraph 7164 and GT1M-V2 was 439 +/- 565 cpm. CONCLUSIONS: There were no statistically significant differences between outputs from all the accelerometers, indicating that researchers can select any of the four ActiGraph accelerometers in doing research.