CONTEXT: Nitric Oxide (NO) is an endothelial-derived vasoactive molecule that causes an increase in blood flow and oxygen delivery to tissue. A reduction in NO bioavailability has been found to occur in adults over the age of 60 and can be reversed pharmacologically by improving NO synthase (NOS) activity. Reversing these age-related changes with alternative interventions, such as aerobic exercise, has shown some promising results. OBJECTIVE: To quantify blood NO-bioavailability (as measured by blood nitrite levels) in a population of aerobically trained elderly men and compare these data to a group of age-matched, inactive individuals. In addition, we measured the cutaneous vasodilator response to local skin heating as a bioassay for NO-mediated cutaneous dilation. SETTING: BYU Human Performance Research Center (HPRC). PARTICIPANTS: 16 healthy elderly men (age = 66 ± 7.07 years) were divided into two groups based on physical fitness levels and estimated VO2max in ml O2•kg-1•min-1 (Trained = 39.1 ± 1.21, Untrained = 29.0 ± 2.70). INTERVENTIONS: A blood sample was collected and analyzed for NO. A microdialysis study was performed and dialysate was collected at 32°C and at 42°C. During the heating process, skin blood flow (skin vasomotor activity) was monitored and reported as cutaneous vascular conductance (CVC). MAIN OUTCOME MEASURES: Whole blood nitrite concentrations, pre- and post-heat nitrite concentrations, and CVCmax were compared between trained and untrained groups. RESULTS: Whole blood nitrite concentration was similar in trained subjects and untrained subjects averaging 25.77 ± 6.75 and 21.43 ± 7.20 µM, respectively (F1,13 = 0.19; P = 0.6671]. Local skin heating had no impact on the concentration of nitrite in dialysate samples ([NOx]dialysate F1,26 = 0.01; P = 0.7567). In addition, the plateau in % CVCmax following 30 minutes of local heating was similar for trained and untrained subjects averaging 67.7 ± 5.8 and 68.0 ± 6.2 % CVCmax, respectively (F1,13 = 0.00; P = 0.9673). CONCLUSIONS: The results of this study indicate that age-mediated reductions in whole blood NO-bioavailability and decrements in NO-mediated cutaneous vasodilation during local heating were similar in aerobically fit and sedentary adults 60 years old or older. We conclude that a commitment to aerobic fitness was unable to overcome the age-related dysfunction of the NOS system.

Generalized joint laxity (GJL), a condition in which most joints of the body move beyond the accepted normal range of motion, is present in many ballet and modern dancers. It has been associated with an increased risk of injury, decreased muscle strength, and greater landing forces. Increased joint laxity results in joint instability and may precede the development of osteoarthritis, which is associated with a reduction in cartilage thickness. We hypothesized that dancers with GJL would have decreased hip cartilage thickness, as well as greater hip adduction angles and greater ground reaction force on landings. Twenty female ballet and modern dancers (mean age: 21.0 ± 1.79 years; mean weight: 57.0 ± 5.71 kg; mean years of dance experience: 14.6 ± 3.53 years; mean hours of training per week: 19.2 ± 7.24 hours) were recruited from college and local dance programs and screened for GJL. Each dancer performed three forward drop landings onto a force plate and received an MRI on their dominant hip. There was a significant difference in hip cartilage thickness, as viewed in the frontal plane (GJL group average: 2.66 ± 0.33 mm; control group average: 3.14 ± 0.48 mm; p = 0.0160), between the groups. There were no significant differences in peak hip adduction angle on landing (GJL group average: 80.9 ± 5.04 degrees; control group average: 77.9 ± 5.78 degrees; p = 0.2269) or peak landing ground reaction force (GJL group average: 5.56 ± 1.28 body weights; control group average: 5.17 ± 0.82 body weights; p = 0.4274) between the generalized joint laxity group and the control group. Dancers with GJL have thinner cartilage at the hip. These results suggest that dancers with GJL may be at a greater risk for injury. Therefore, these dancers may benefit from strength training programs, rather than flexibility training, to help counteract the joint instability that can lead to injury.

Physical activity impacts health and disease in multiple body tissues including the intervertebral discs. Fluid flow within the disc is an indicator of disc health that can be observed using diffusion weighted magnetic resonance imaging. We monitored activity levels of 26 participants, age 35 to 55 yrs, using Actigraph accelerometers for four days to evaluate vigorous-intensity activity, moderate to vigorous-intensity activity, and sedentary time. Participants underwent structural and diffusion weighted magnetic resonance imaging to evaluate intervertebral disc health and fluid flow. They also underwent bone density scans, carotid artery ultrasounds, a treadmill test, and a physical exam for pain, range of motion, and instability. These measures were used to correlate MRI indicators of intervertebral disc health with participant activity. Participants with any vigorous-intensity physical activity compared with no vigorous-intensity activity had significantly greater L5/S1 apparent diffusion coefficient values (p = 0.002), corresponding to higher freedom of diffusive movement for cellular nutrients and metabolic waste. Sagittal T2 values in the L5/S1 were also higher (p = 0.004), corresponding to higher water content in the discs. Higher apparent diffusion coefficients were also found in participants with more than 30 minutes compared with less than 30 minutes of daily moderate to vigorous physical activity (p = 0.03), and in participants with less than 67% awake time as sedentary time compared with more than 67% sedentary time (p = 0.03). Increased dynamic loading through physical activity and decreased static loading from sedentary time benefit intervertebral disc health. Physical activity, particularly vigorous activity, is beneficial in helping maintain intervertebral disc health.

Introduction: Irish dance has evolved to become more athletically demanding, thus making the art form very hard on dancers' bodies. Irish dancers must land from difficult moves without letting their knees bend or heels touch the ground, causing large amounts of force to be absorbed by the body. Past studies have found dancers landing with a range of 4.5–6 times body weight, potentially causing high amounts of overuse injury. The majority of injuries incurred by Irish dancers are due to overuse (79.6%). The landings that occur in Irish dance have been minimally evaluated in current literature. Obtaining values of vertical ground reaction forces (GRFs) produced by Irish dancers will assist in understanding the causes of overuse injuries, fill significant gaps in the current literature, and identify which Irish dance moves should be used less frequently to possibly reduce the chance for overuse injury. Purpose: To determine vertical GRFs produced by female Irish dancers in hard and soft shoes during common movements. The purpose of this study was to determine peak force, rise rate of force, and impulse in selected Irish hard shoe and soft shoe dance movements. Materials and Methods: Sixteen female Irish dancers between 14 and 25 years of age were recruited from the 3 highest competitive levels. Each performed a warm-up, reviewed 8 common Irish dance moves, and then performed each move 3 times upon a force plate. Four moves each were performed in soft and hard shoes. GRFs were measured using a 3-dimensional force plate running at 1000 Hz. Peak force, rise rate, and vertical impulse were all calculated. It was hypothesized that the 8 moves would produce different GRFs. Results: Peak forces normalized by each dancer's body weight were significantly different across moves (F = 65.4, p < 0.01; F = 65.0, p < 0.01; and F = 67.4, p < 0.01 respectively). Years of experience was not correlated with peak force, rise rate, or impulse (p < 0.40). Conclusion: There is a large range in peak forces created by Irish dancers. Moves that have high average peak forces may have a higher risk in causing overuse injuries. All dancers should take care to limit the use of these moves in their choreography to prevent such injury.

The circadian system controls 24-hour cycles of behavior and physiology, such as rest-activity and feeding rhythms. The human circadian system synchronizes with, or entrains to, the light/dark cycle (sunrise/sunset) to promote activity and food consumption during the day and rest at night. However, strict work schedules and nighttime light exposure impair proper entrainment of the circadian system, resulting in chronic circadian misalignment. Numerous studies have shown that chronic circadian misalignment results in poor health. Therefore, therapeutic interventions that could shift circadian rhythms and alleviate circadian misalignment could broadly impact public health. Although light is the most salient time cue for the circadian system, several laboratory studies have shown that exercise can also entrain the internal circadian rhythm. However, these studies were performed in controlled laboratory conditions with physically-active participants. The purpose of this study was to determine whether timed exercise can phase advance (shift earlier) the internal circadian rhythm in sedentary subjects in free-living conditions. Fifty-two young, sedentary adults (16 male, 24.3±0.76 yrs) participated in the study. As a marker of the phase of the internal circadian rhythm, we measured salivary melatonin levels (dim light melatonin onset: DLMO) before and after 5 days of timed exercise. Participants were randomized to perform either morning (10h after DLMO) or evening (20h after DLMO) supervised exercise training for 5 consecutive days. We found that morning exercisers had a significantly greater phase advance than evening exercisers. Importantly, the morning exercisers had a 0.6h phase advance, which could theoretically better align their internal circadian rhythms with the light-dark cycle and with early-morning social obligations. In addition, we also found that baseline DLMO, a proxy for chronotype, influenced the effect of timed exercise. We found that for later chronotypes, both morning and evening exercise advanced the internal circadian rhythm. In contrast, earlier chronotypes had phase advances when they exercised in the morning, but phase delays when they exercised in the evening. Thus, late chronotypes, who experience the most severe circadian misalignment, may benefit from exercise in the morning or evening, but evening exercise may exacerbate circadian misalignment in early chronotypes. Together these results suggest that personalized exercise timing prescriptions based on chronotype could alleviate circadian misalignment in young adults.

The purpose of this investigation was to determine the effects of two speeds of isokinetic training on muscular strength, power and endurance on college females. The study involved thirty college females. Twenty of the subjects who served in the experimental groups were randomly assigned to one of two groups: fast speed or slow speed group. This was done after matching based on the pretest strength measure. Ten subjects who served as the control group were from a bowling class This investigation was conducted for seven weeks with a training frequency of three days per week. The experimental treatment was isokinetic training for right and left knee extensions. There were three sets of repetitions; each set lasted twenty seconds with a thirty second rest period between each set. The dependent variables measured were strength, Power I, Power II and muscular endurance for the right and left knee extension. Analysis of variance was used to determine differences between the groups on pretest measures. A comparison of the pretest and posttest means was made to determine differences resulting from training. Analysis of covariance was used for the posttest measures with pretest measures as covariates for the eight dependent variables. Results of statistical analysis indicated that no significant differences existed on the pretest treasures between the three groups in the eight variables with the exception of Power I for the right knee and endurance measure for the left knee extension. Posttest analysis revealed significant differences in all the eight dependent variables between the experimental groups and the control group. Also, significant differences existed between the fast speed and the slow speed groups for six of the eight variables. There were no significant differences on the strength measures between the experimental groups. The isokinetic training method was found to be effective in developing strength, power and muscular endurance. Also, the isokinetic fast speed was found to be a more effective way of bringing about power and muscular endurance development.

The purpose of this study was to determine if the Female Athlete Screening Tool (FAST) is a valid indicator of the three physical components of Female Athlete Triad (FAT), malnutrition, amenorrhea, and low bone mineral density, and if administration of the FAST can be used as a time- and cost-effective way to identify FAT. Participants completed the FAST, the Menstrual Status Questionnaire, and had a blood sample drawn. Interpretation of the total FAST score placed participants in one of three conditions: normal, subclinical disordered eating, or clinical eating disorder. The presence of the three biomarkers of FAT was determined by participants’ responses on the Menstrual Status Questionnaire and protein analyses of their blood samples, in which plasma Prealbumin and CTx levels were tested. Results indicated that there were not significant differences between total FAST scores of participants in each of the groups for any of the three biomarkers (i.e., low versus normal Prealbumin levels; amenorrhea versus normal menstruation; high versus normal CTx levels). More research is needed before it can be determined if the FAST is an appropriate diagnostic tool for FAT. An overwhelming majority of the sample (79.5%) received total FAST scores that fell in the subclinical disordered eating or clinical eating disorder ranges, which supports previous findings that female athletes are at a high risk of developing disordered eating habits or eating disorders due to their unique characteristics and lifestyles.

Many college students exercise individually or participate in collegiate and intramural sports in addition to fulfilling their stressful academic requirements. The combination of accumulated stress and vigorous exercise could result in an impaired immune system, prompting the onset of disease and absences in class and sports practice. Twenty-six male and female participants aged 18 to 23 were recruited for this study. Over the course of an academic semester, participants completed weekly electronic surveys documenting stress levels, aerobic exercise, and symptoms related to upper respiratory tract infections. Participants were evaluated at four different time points (Baseline, Post-Midterm Exam, Baseline Reassessment, and Post-Final Exam) for body fat percentage, cardiovascular fitness, heart rate, blood pressure, and a 10mL blood draw. Blood samples were used to measure blood glucose, cortisol, IL-6, and CD11b levels. Analysis of cortisol and IL-6 concentrations required ELISA kits for protein quantification in plasma samples. CD11b levels in peripheral blood mononuclear cell samples were measured by Western Blot analysis. There was a significant increase in blood pressure during the final exam compared to rest for systolic (p=0.005) and diastolic (p=0.004) blood pressures. There was a significant decrease in anxiety during the final exam compared to anxiety during the mid-term exam (p=0.022). The acute stress of an exam was strong enough to illicit physiologic blood pressure change, but the chronic stress throughout the semester was not intense enough did not illicit physiologic or immune responses. The volume of aerobic exercise in the vigorous workout group was not great enough to influence immune responses nor disease incidence.

Variable Resistance Training (VRT), loading elastic band tension on a barbell, has shown improvements in force, power, and velocity. Studied extensively in the squat and bench press, VRT is less researched in the context of the deadlift. Additionally, while no acute VRT deadlift studies exist where intensity was ≥ 90% 1- RM, some heavy VRT studies suggest that at approximately 90% 1-RM, less band tension (BT) is required to enhance force and power than seen at lower intensities in existing research. Therefore, the purpose of this study was to determine the effects of VRT on peak relative vertical ground reaction force (VGRF), average and peak velocity, and time of peak force (VGRF time), in heavy, traditional deadlifts. METHODS: Seven resistance trained, college-aged males were recruited for this study. Over the course of approximately eight weeks, subjects completed five training sessions including familiarization, and testing the deadlift at 90% 1-RM with no bands (NB), 10%BT, 20%BT, or 30%BT. All training sessions were performed on dual force plates and with a linear position transducer to determine kinetic and kinematic outcomes. RESULTS: There were significant differences between conditions for both peak [F (3,18) = 13.607, p < 0.001] and average velocity [F (3, 18) = 14.077, p < 0.001]. No significant differences were detected between conditions for peak relative VGRF [F (3, 12) = 2.41, p= 0.118], or VGRF time [F (3, 12) = 1.843, p= 0.193]. PRACTICAL APPLICATIONS: The results of this study suggest velocity is improved with 20% to 30%BT when deadlifting approximately 90% 1-RM. For maximum force, traditional, NB deadlifts might be optimal considering the lack of improvement with the addition of bands. Despite the lack of significance between conditions, the large relative percent decrease in VGRF time from NB to 10%BT suggests that this small amount of BT may be advantageous for rapid force development with heavy loads

Autophagy is a major degradation mechanism, responsible for clearing damaged and dysfunctional organelles, including the endoplasmic reticulum, a structure essential for protein synthesis and myocellular hypertrophy. Alterations in autophagy throughout various tissues of the body have been linked to various negative side effects such as decreased myocellular hypertrophy and insulin resistance. High fat diets lead to changes (both increases and decreases) in autophagy in various tissues throughout the body in a tissue-specific manner. Skeletal muscle autophagy is decreased in myotubes cultured from obese women, however the mechanism by which this occurs is unknown. As the largest organ system in the human body, skeletal muscle serves an important role in overall metabolic health. Therefore, sufficient skeletal muscle autophagy is important for proper metabolic function. Moreover, a decrease in liver and pancreas autophagy has been found to lead to endoplasmic reticulum (ER) stress and the development of insulin resistance. Understanding the relationship between autophagy and ER stress in the skeletal muscle following a high fat diet may help elucidate a novel target for decreasing negative side effects. Interestingly, both acute and chronic exercise have been shown to increase skeletal muscle autophagy. This points to a potential therapeutic treatment for those suffering with decreased skeletal muscle autophagy and may help improve ER stress. The purpose of this study was to compare the in vivo and in vitro effects of high fat exposure on skeletal muscle autophagy. Additionally, the relationship of autophagy and ER stress in skeletal muscle was explored. Lastly, this project identified changes in skeletal muscle autophagy and ER stress following cyclic stretch, an in vitro model of exercise in C2C12 myotubes. Eight-week-old C57BL/6J were fed a high fat diet for 16 weeks and tibialis anterior muscle examined for changes in autophagy markers. Gene expression (mRNA content) of autophagy markers Atg3 (p=0.011, fold change 1.37), Atg12 (p=0.026, 1.38), and Atg16L (p=0.004, 1.49) were increased in skeletal muscle of obese mice. Protein content was also measured, where increases in Atg3 (p = 0.04, 1.22), Atg12 (p = 0.027, 1.21), and Atg16L1(p = 0.021, 1.59) were found. However, there was no difference in LC3 II:I ration. No changes were seen in Atg5 or LC3. Additionally, C2C12 myotubes were treated with equimolar palmitate and oleate for 24h then assessed for mRNA content of genes involved in autophagy and ER stress. Autophagy genes Atg5 (p = 0.007, fold change 1.78), Atg12 (p = 0.001, fold change 1.99), and LC3 (p = 0.01, fold change 2.02) were decreased with high fat treatment. Paradoxically, there was an increase in Atg16L (p = 0.005, fold change 1.90). There were no changes in protein content. ER stress was increased indicated by an increase of sXBP1 (p = 0.005, fold change 1.33). Furthermore, inhibition of autophagy lead to changes in ER morphology and ER stress. To identify the impact of cyclic stretch on skeletal muscle autophagy and ER stress, C2C12 myotubes were subjected to 30 minutes of equibaxial stretch and examined for changes in autophagy and ER stress. Autophagy flux, measured by tyrosine release, increased by 34% (p = 0.04) following exercise and ER stress was decreased. In conclusion, this study provides the novel finding that decreased skeletal muscle autophagy is sufficient for inducing ER stress. Additionally, cyclic stretch increases autophagy and improves ER homeostasis.