Changes In Femoral Neck Bone Mineral Density: A Comparison Of NHANES 2005-2006, 2007-2008, And 2009-2010

Bone mass is an important component of quality of life and can be influenced by lifestyle factors, such as physical activity and diet. However the US surgeon general found a growing portion of Americans are not engaging in adequate amounts of physical activity and/or consuming less calcium and vitamin D. The purpose of this study was to compare bone mineral density (BMD) of American adults of different ethnicities and time periods to detect any differences. It was hypothesized that BMD would be lower in participants from more recent years, and African Americans would have the highest BMD. Measurements were taken at the femoral neck of volunteers between 18 and 35 years of age (n = 3578) from 2005-2006 (n = 1160), 2007-2008, (n = 1135), and 2009-2010 (n = 1283) by the National Center for Health Statistics. The data was analyzed using a three-way independent ANOVA with an alpha level of .05. Femoral neck BMD was used as the dependent variable; and year, age, and race were independent variables. The study found Hispanic women to have a significantly higher BMD from 2005-2006 (p \u3c.05) when compared to participants from later years. In addition, the study found significant differences based on age and ethnicity (p \u3c .001). African-American men (p \u3c .001) and women (p \u3c.001) had a higher BMD than any other ethnicity. Moreover, Hispanic men had a higher BMD (p \u3c.001) than Caucasian men. In men, BMD significantly decreased in each age group (p \u3c.001); whereas in women a significant decrease was detected in every other age group (p \u3c .05). However, in contradiction to literature, the results found peak BMD to occur between 18 and 19 years of age as opposed to mid-to-late twenties

The Analysis of Two Different Types of Tapers on Exercise Performance

The purpose of this study was to compare the differences in a step taper and an exponential decay taper across time. The subjects were randomly divided into two groups, the step (n = 9) or exponential decay (n = 11) group. The participant’s baseline tested, trained for 4 weeks, pre tested, tapered for one week, and then post tested. The exponential group (15.56 ± 1.33; 10.64 ± 1.21) had a significantly lower RPE compared to the step group (16.20 ± 2.68; 11.13 ± 0.64) in stage 4 of the pretest and in stage 2 of the posttest (p ≤ .05). The exponential group (107.22 ± 15.06; 127.33 ± 22.25) had a significantly higher HR compared to the step group (103.71 ± 7.41; 125.14 ± 13.50) in stage 1 and 2, of the pretest (p ≤ .05). In conclusion, there is no significant benefit for one taper over the other

The Relationship of Physiological and Fitness Variables to Performance in CrossFit®-based Exercise: Preliminary Findings

CrossFit® is a rapidly expanding exercise program as well as an emerging competitive sport. Little is known regarding the correlation of physical fitness measures and performance in CrossFit®-based events. PURPOSE: The purpose of this study was to determine the relationship between various physiological and fitness variables and performance in a typical CrossFit®-based workout. METHODS: Nine male participants (age = 32.2 ± 3.6 yrs; height = 173.1 ± 9.8 cm; weight = 86.1 ± 11.6 kg; BMI = 28.6 ± 1.2 kg/m2) who had performed CrossFit® as their primary exercise program at least 3 days/week for the past 12 months were recruited. Participants performed a test of maximal aerobic fitness (VO2max), a Wingate test, a DEXA scan, a 1RM Clean and Jerk, and a series of exercises that would typically be included in a CrossFit®-based workout. More specifically, participants performed 15 Wall Ball exercises (20 lbs.), 15 Box Jumps (24 in.), 10 Burpees over a barbell, and 10 Kipping Pullups. If all exercises were completed, the participants repeated the exercises in the same order. The participants were asked to stop after 12 min, and the total number of repetitions completed was recorded. Questions regarding the participants’ exercise history and dietary habits were asked. Spearman’s correlation was used to identify relationships between the variables and performance (number of repetitions completed) during the CrossFit®-based workout. Participants were also grouped into “high” (≥ median) or “low” (\u3c median) groups, and independent samples t-tests were used to compare how each group performed during the CrossFit®-based workout. Statistical significance was set at .05. RESULTS: Performance during the CrossFit®-based workout had strong, positive relationships with strength-to-body weight ratio (r = .686; p = .041), 1RM Clean and Jerk (r = .915; p = .001), and years of experience (r = .869; p = .002). Participants with higher strength-to-body weight ratios (p = .036), lower fatigue index (p = .022), lower body fat percentage (p = .022), higher weight lifted during the 1RM Clean and Jerk (p = .017), and more years of experience (p = .027) completed more repetitions during the CrossFit®-based workout. Significance was not found with any other variable. CONCLUSION: Based on these early findings, anaerobic fatigue resistance, body fat percentage, muscular power, and exercise history appear to be significant predictors of performance in CrossFit®-based workouts

Training Manipulations Based on Acute Heart Rate Variability Measures

Heart rate variability (HRV) is an accurate indicator of sympathetic and parasympathetic nervous system activity. The balance between these systems affects the time between heartbeats. A high variability between heartbeats is equated to a greater influence from the parasympathetic nervous system. In this state, an individual is well rested, and therefore possesses higher readiness to perform physical activity. Through the use of smartphone applications (apps), athletes and coaches can collect accurate short-term HRV readings to assess autonomic nervous system balance. These apps provide a readiness to train score that may prove beneficial in adjusting daily training loads to maximize performance. PURPOSE: The purpose of this study is to characterize the changes in lower-body strength and power before and after a 6-week strength training program while manipulating intensity based on daily HRV readiness measures in female collegiate softball athletes. METHODS: Nine female NCAA Division II Softball athletes completed the 6-week training protocol. Participants were split into an experimental group (E; n = 5; age = 20.5±0.7 yrs, height = 166.9±2.7 cm, weight = 59.9±7.6 kg), who completed the training with the intensity adjusted based off of daily HRV readiness scores, and a control group (C; n = 4; age = 20.6±0.8 yrs, height = 171.7±1.2 cm, weight = 70.7±30.3 kg), who completed the training with no changes in exercise intensity. Measures of HRV were taken prior to each training session and used to calculate readiness scores with the use of a smartphone app. Participants completed 3 strength-training sessions per week throughout the study. Lower-body strength and power measurements were assessed before and after the protocol. One-repetition maximums on the back squat (SQ) and clean (CL) exercises and maximum vertical jump (VJ) height were collected. RESULTS: Lower-body power measurements were increased in the E group (CL: 51.3 vs. 56.9 kg, p = 0.047; VJ: 40.1 vs. 44.7 cm, p = 0.037) and the C group (CL: 56.8 vs. 63.6 kg, p = 0.021; VJ: 41.6 vs. 46.2 cm, p = 0.034), following 6 weeks of strength training. No significant differences were observed in lower body strength measurements in the E group (SQ: 74 vs. 84.1kg, p = 0.21) or the C group (SQ: 75.5 vs. 86.6 kg, p = 0.2). Significant differences were found between the prescribed volume of training and the completed volume of training (25364 vs 21650 kg, p = 0.014) in the E group. No significant differences (p \u3e 0.05) were found with SQ, CL, and VJ measures between the E and C groups following 6 weeks of strength training. No significant differences (p \u3e 0.05) were found in daily HRV measures between the E and C groups. CONCLUSION: Both groups exhibited similar HRV scores throughout the 6-week training protocol. Using daily short-term HRV readings, training intensity can be reduced without leading to any differences in lower-body strength and power improvements in female collegiate softball athletes

Mitochondrial Biogenesis is Dysregulated in Thyroid Hormone Depleted Muscle Cells Despite Stimulatory Effects of Formoterol

Skeletal muscle (SKM) is an important regulator of metabolism and adaptations from exercise training influences mitochondrial function. Thyroid hormone (TH) is a regulator of SKM processes, including mitochondrial biogenesis. PURPOSE: To use an in vitro model of hypothyroidism to test the hypothesis that SKM cells will have dysregulated mitochondrial homeostasis. Additionally, the exercise mimetic, formoterol, was used to determine the effects of exercise signaling on mitochondrial biogenesis. METHODS: Human SKM myoblasts (n = 6 per group) were cultured and differentiated until mature myotube formation (Day 6). Groups included control cells (CON), TH depleted cells (ThD), and TH depleted cells plus formoterol stimulation (ThD+F; 30nM for 3h). Total RNA was extracted during mid-myogenesis (Day 4) and at terminal differentiation (Day 6). Gene expression for Peroxisome Proliferator-Activated Receptor Gamma Coactivator-1 Alpha (PGC-1α), Mitochondrial Transcription Factor A (TFAM), and Nuclear Respiratory Factor 1 (NRF1) was determined by qPCR. Data was analyzed by repeated measures ANOVA. RESULTS: PGC-1α: D4 ThD was decreased compared to D4 ThD+F (-4.6); D4 ThD+F was increased compared to D4 CON (4.6); D6 CON was decreased compared to D6 ThD+F (-2.9); D6 ThD was decreased compared to D6 ThD+F (-3.7). TFAM: D4 ThD+F was greater than D4 CON (3.6); D4 ThD+F was greater than D6 ThD+F (3.6); D6 ThD was decreased compared to D6 CON (-0.55); D6 ThD+F was decreased compared to D6 CON (-0.63). NRF1: D4 ThD was decreased compared to D4 CON (-0.31); D4 ThD was greater than D4 ThD+F (0.36); D4 ThD was greater than D6 ThD (0.17); ThD+F was decreased compared to D4 CON (-0.67); D6 CON was decreased compared to D4 CON (-0.18); D6 ThD was decreased compared to D6 CON (-0.3); D6 ThD+F was decreased compared to D6 CON (-0.42). All reported differences are significant (p \u3c 0.05). Data are expressed as fold changes. CONCLUSION: ThD media resulted in reduced NRF1 signaling in both D4 and D6 with a subsequent decrease in D6 only for TFAM. Formoterol resulted in the expected stimulation of PGC-1α at both D4 and D6, but subsequent signaling for genes associated with mitochondrial biogenesis common to PGC-1α stimulation were lost as a result of TH depletion at D6 only for TFAM and both D4 and D6 for NRF1

Formoterol Stimulation In Vitro Influences Myogenic Regulatory Factors During Myogenesis in Human Skeletal Muscle Cells

The process of myogenesis within skeletal muscle (SKM) is essential for growth and repair and is coordinated via the expression of myogenic regulatory genes. Previous animal studies have reported that formoterol, a beta-adrenergic receptor agonist, has stimulating effects on genes related to SKM mitochondrial function and biogenesis, similar to effects found for exercise. Lesser known is the potential “exercise mimetic” influence that formoterol stimulation may have during the stages of myogenesis, especially in human SKM cells. PURPOSE: To investigate the effects of formoterol stimulation on expression of myogenic regulatory genes during myogenesis in human SKM cells. METHODS: Human SKM myoblasts (n = 6 per group) were cultured and differentiated until mature myotube formation (Day 6). Groups included control cells (CON) and cells stimulated by 30nM formoterol for 3h prior to RNA extraction points (FORM). Total RNA was extracted during mid-myogenesis (Day 4) and at terminal differentiation (Day 6) (a cell culture model of investigating myogenesis). Gene expression for Myogenic factor 5 (Myf5), Myogenic differentiation 1(MyoD), and Myogenin (MyoG) was determined by qPCR. Data was analyzed using repeated measures ANOVA. RESULTS: Myf5: There was no change for either condition for D4. D6 CON was lower than D4 CON (-0.25). D6 FORM was greater than D4 FORM (0.65) and D6 CON (0.75). MyoD: D4 FORM was lower than D4 CON (-0.57). D6 FORM was greater than D4 FORM (0.85) and lower than D6 CON (-0.16). D6 CON was lower than D4 CON (-0.33). MyoG: D4 FORM was lower than D4 CON (-0.72). D6 CON was lower than D4 CON (-0.44). D6 FORM was lower than D6 CON (-0.24). All reported differences are significant (p \u3c 0.05). Data are expressed as fold changes. CONCLUSION: As expected, for the CON group, Myf5, MyoD, and MyoG expression all decreased from D4 mid-myogenesis to D6 terminal myogenesis, indicating finalization of the myogenic gene program. For the FORM group, Myf5 expression was elevated at D6 compared to CON while MyoG and MyoD expression was lower than CON for D4 and D6. The interpretation is that FORM stimulation increased stimulus of D4 myoblast proliferation and, thus, delayed initiation of differentiation. These results, coupled with other preliminary data from our lab showing increased mitochondrial biogenesis with this model of investigation, suggests that this exercise mimetic stimulation may cause shift in the cell towards bioenergetic preference rather than fusion of myotubes

Acute Cardiovascular and Metabolic Responses to Three Modes of Treadmill Exercise in Older Adults with Parkinson’s Disease

Parkinson’s disease (PD) is a neurodegenerative condition characterized by muscle tremors, rigidity and dyskinesis leading to balance and gait abnormalities that could alter physiologic responses during exercise. Locomotion on an aquatic treadmill (ATM) or anti-gravity treadmill (AGTM) may be a safe alternative to exercise on a traditional land treadmill (LTM) in those with PD. PUPROSE: To determine the acute cardiovascular and metabolic responses to three different modes of treadmill exercise in older adults diagnosed with Parkinson’s disease. METHODS: Eight adults diagnosed with PD (68 ± 3 years of age) completed one exercise session on an LTM, one session on an ATM, and one session on an AGTM at 50% body weight. Participants walked from 1 to 3 mph in 0.5 mph increments at 0% grade during each exercise session. Heart rate (HR), energy expenditure (EE), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured at rest and during steady-state exercise at each speed on each treadmill. Rate of perceived exertion was also measured during steady-state exercise. Rate pressure product (RPP) was calculated. RESULTS: All variables, with the exception of DBP, increased as speed increased across all treadmill modes (p \u3c 0.001). Between treadmill modes across all speeds, EE was statistically different (p = 0.025). There was a significant interaction effect for mode and speed for HR (p \u3c 0.001) and RPP (p = 0.003). At all speeds except 1.5 mph, HR was higher on the LTM versus the AGTM (p \u3c 0.05). CONCLUSION: Exercising on an ATM or an AGTM elicits similar physiologic responses to exercise on an LTM in adults with P

Changes in Balance, Gait and Motor Skills Following Treadmill Exercise in Adults with Parkinson’s Disease

Locomotion on an aquatic treadmill or anti-gravity treadmill may be a safe and effective alternative to exercise on a traditional land treadmill in those with Parkinson’s disease as the removal of body weight in these environments may allow the participant to exercise with less concern of falling at higher speeds before reaching volitional fatigue. PURPOSE: To determine the training effects of three different treadmill modalities on dynamic balance, gait, and fine motor control in older adults diagnosed with Parkinson’s disease. METHODS: Ten adults diagnosed with Parkinson’s disease (70 ± 5 years of age) completed 8 exercise sessions (4 weeks, 2x/week) each separately on a land treadmill, aquatic treadmill, and anti-gravity treadmill at 50% body weight. Two weeks separated each intervention and the order was randomized. A 4-week control period occurred at the start of the study in which no treadmill exercise was performed. Each exercise session included a 2-minute warm-up and 30 minutes at a moderate intensity. Before and after each intervention, balance, gait and fine motor control were measured. Dynamic balance and gait were assessed using a Timed-Up-and-Go test and Performance Oriented Mobility Assessment (POMA). Fine motor control was assessed with the Purdue Pegboard Test. RESULTS: The gait assessment of the POMA was significant across all time points (p = 0.028). All other variables were statistically similar (p \u3e 0.05) across all time points. CONCLUSION: Exercising on a traditional land treadmill, aquatic treadmill, or anti-gravity treadmill for 60 min/week for 4 weeks at a moderate intensity did not alter balance, gait or fine motor control in adults with Parkinson’s disease

Physiological Responses to Running on a Land and Anti-gravity Treadmill

Walking or running using partial body weight support can be a valuable rehabilitation tool when individuals are unable to exercise at full weight bearing capacity due to injury or pain. An anti-gravity treadmill (AGT) can provide varying levels of unweighting to effectively reduce the loads on the lower extremity. PURPOSE: To determine differences between cardiorespiratory responses while running on a land treadmill and on an anti-gravity treadmill (AGT) during 30 min of exercise followed by a run to volitional fatigue. METHODS: Participants (n=12, age=22.0 ± 4.3 years, weight=68.0 ± 13.0 kg) completed four visits (1 familiarization session and 3 testing sessions) with a minimum of 48 hours between each visit. The participants were asked not to consume stimulants (e.g., caffeine), and not to perform any exercise on the days of the familiarization and testing sessions. During the familiarization session, participants completed a submaximal treadmill test, two sessions on the AGT to determine the speed needed to reach 65-70% HRR for two different body weight percentages (70% and 90%), and a run on the land treadmill to determine the speed needed to reach 65-70% HRR and 95-100% HRR. A 15-min rest period was provided between each activity. Participants returned to the lab for three additional exercise sessions consisting of running on a land treadmill and on an AGT at 70% and 90% body weight. Each testing session consisted of a 2 min self-paced warm-up at 0% grade, followed by running for 30 min at 65-70% HRR at 0% grade, followed by running to volitional fatigue at 95-100% HRR at 0% grade. Heart rate, oxygen consumption (VO2), respiratory exchange ratio (RER), and rate of perceived exertion (RPE) were measured at 15 min, 30 min and exhaustion. Blood lactate concentration, energy expenditure (EE) and total time to exhaustion (TTE) were recorded when the participant reached volitional fatigue. RESULTS: When compared to land treadmill exercise, VO2 was significantly lower at 70% AGT (32.6 ± 9.5 vs. 41.1 ± 10.8 ml/kg/min; p=0.002) and 90% AGT (36.3 ± 10.2 vs. 41.1 ± 10.8 ml/kg/min; p=0.026). Oxygen consumption was significantly lower at 30 min when compared to TTE (31.5 ± 7.8 vs. 41.9 ± 10.6 ml/kg/min; p\u3c0.001) for all conditions. A significant interaction for condition x time (p\u3c0.01) for RER was found. Simple effects analysis indicated RER was lower at 30 min when compared to TTE for 70% AGT (0.86 ± 0.07 vs. 0.90 ± 0.06; p=0.005), 90% AGT (0.84 ± 0.05 vs. 0.91 ± 0.07; p=0.002), and land treadmill (0.85 ± 0.06 vs. 1.02 ± 0.09; p\u3c0.001). At TTE, RER was lower when compared to the land treadmill for 70% AGT (0.90 ± 0.06 vs. 1.02 ± 0.09; p=0.002) and 90% AGT (0.91 ± 0.07 vs. 1.02 ± 0.09; p=0.007). Energy expenditure was not significantly different for the three conditions (p=0.355). CONCLUSION: When running at partial body weight, individuals may be able to achieve similar energy expenditure compared to running on a land treadmill; however, they may be running at a lower VO2 on the AGT