The Effect of Acute Hyperglycemia on Muscular Strength, Power and Endurance

International Journal of Exercise Science 10(3): 390-396, 2017. The purpose of this study was to elucidate the impact of acute hyperglycemia on skeletal muscle strength, power, and endurance. Ten male collegiate athletes (age 21.5 ± 1.5 years, height 186 ± 2.03 cm, body mass 108.8 ± 7.6 kg) participated in 2 testing sessions, separated by 7 days and randomized for either high glucose (HG) or control (C) treatment conditions. HG consumed a high glucose drink (2 g glucose/kg body weight) while controls consumed an isocaloric nutrition bar (40% protein, 30% fat, and 30% carbohydrate). Blood glucose (BC) levels for HG and C were tested at 0 (basal) and 30, 60, 90, and 120 minutes (mins) post consumption. At 30 mins post consumption, HG and C muscular strength was assessed by a 1RM bench press (BP) test followed by lower body power at 60 mins via vertical jump test. Muscular endurance was examined with a 3-set-to-failure BP test at 90 mins. HG exhibited significantly greater BC values (

Acute Ultraviolet Light Exposure and Post-Resistance Exercise Serum Testosterone: A Pilot Study in Older Men

International Journal of Exercise Science 13(2): 607-614, 2020. Testosterone deficiency is linked to a multitude of conditions including depression, sexual dysfunction, and cognitive impairment. Although synthetic testosterone-boosting pharmaceuticals have gained wide use, recent data suggests that vitamin D, ingested orally, may positively impact serum testosterone. Furthermore, evidence tying ultraviolet (UV) light exposure to endogenous vitamin D synthesis presents an intriguing possibility for naturally enhancing serum testosterone. This investigation sought to determine the effect of acute UV light exposure on resistance exercise-induced acute testosteronemia and vitamin D in older men. Six older adult men of varying activity levels (age 62 ± 1.79 yrs., height 179.92 ± 1.12 cm., body mass 83.79 ± 3.12 kg., BMI 25.95 ± 1.15 kg/m2) participated in two testing sessions separated by one week: 1) Resistance exercise followed by standard passive recovery (RERC) and 2) RE plus UV light exposure during the first 10-minutes of RE passive recovery (RERC-UV). The RE protocol was identical in both sessions and consisted of four sets of 10RM on leg press, chest press, and back row with 1-minute of rest between sets followed by 30-minutes of post-RE passive recovery. Serum testosterone and vitamin D were measured pre- and post-RE in 5-minute increments during the 30-minute recovery. Analysis of variance revealed neither RE or RERC-UV significantly affected serum testosterone or vitamin D. These findings suggest that acute UV light exposure may be insufficient to positively impact serum testosterone and vitamin D following a single bout of RE in older adult men

The Effects of Elevation Gain on the Pack Hike Test: Implications for Interagency Hotshot Crews

It is unknown if administering a graded load carriage task, which more closely mirrors the occupational circumstances wildland firefighters are exposed to, improves the validity of the Pack Hike Test and its’ ability to differentiate between the fitness profiles amongst Interagency Hotshots (IHC) and type 2 crews. PURPOSE: The aim of the current study was to examine the performance differences and HR responses between IHC and type 2 crews when completing a maximal effort graded load carriage task. METHODS: This study compared performance outcome measures amongst two classes of hand crews, Type 1 (IHC; n=12) and Type 2 (T2C; n=7). All participants engaged in one maximal effort hike test, which covered 1.3 miles with a 16.5% grade while carrying a 45 lb. load carriage system. Additionally, participants were instructed to complete the hike at a maximal pace and were given no feedback or motivation during the execution of the test. Immediately following the termination of the test, participants were instructed to perform a supine 1-minute recovery period. Participants wore Polar H10 monitors in order to collect the following variables: Pace (min/mile), HR recovery (bpm), HR average (bpm) and HR max (bpm). RESULTS: There were no significant differences between groups for any of the performance or HR response variables (p\u3e.05). Compared to T2C, IHC pace (-2.07 min/mile) as well as HR recovery (+3.00 bpm) values trended towards increased performance. Additionally, a tendency emerged for IHC members to sustain higher physiological stress, as indicated by greater relative HR average (+8.18 bpm) and HR max (+8.51 bpm) values. CONCLUSION: IHC, compared to T2C, showed a slight positive trend in their ability to sustain maximal work rates for a longer duration, thus resulting in improved hiking performance. A maximal effort graded load carriage test may provide a better understanding of occupational fitness amongst wildland firefighters

The Prevalence of Physical Inactivity and Low Back Pain in Sedentary Office Employees: A Survey Analysis

Low back pain (LBP) is an increasingly common chronic condition and self-perceived disability that full-time sedentary employees are at risk of being exposed to. Sedentary employees are paid workers who fulfill all or most of their occupational duties seated. Currently, there is very little research available that discusses how physical inactivity affects LBP in sedentary office employees. PURPOSE: The purpose of this study is to: (1) determine the prevalence of LBP pain among sedentary office employees, (2) identify the number of sedentary employees who meet the current physical activity guidelines outlined by the American College of Sports Medicine (ACSM) and mirroring Physical Activity Guidelines for Americans, and (3) to determine the prevalence of LBP amongst physical activity habits in the surveyed population. METHODS: One hundred sixty-four participants completed the 36-question survey. Survey questions assessed past injuries, working history, chair type, exercise history and training frequency, sedentary habits, and pain prevalence and management. RESULTS: The survey found 73.7% of participants experience some level of LBP when seated at work. Additionally, 32.3% of participants were inactive, 57.9% of participants were insufficiently active, 7.9% of participants were active and 1.8% of participants were highly active in accordance with the Physical Activity Guidelines for Americans. Sixty-six participants reported engaging in resistance training with 63.6% reporting LBP. Ninety-five participants reported engaging in aerobic activity with 75.7% reporting LBP. Eighty-nine participants reported engaging in core training with 70.7% reporting LBP. CONCLUSION: The majority of sedentary office employees reported LBP. Additionally, only ~10% of survey respondents met or exceeded ACSM’s Physical Activity Guidelines and LBP was still prevalent in most participants despite their engagement in physical activity

A Comparison of Muscle Activation Among the Front Squat, Overhead Squat, Back Extension and Plank

International Journal of Exercise Science 13(1): 714-722, 2020. The purpose of this study was to compare the muscle activation of the scapula, leg, and trunk among the front squat (FS), overhead squat (OHS), back extension (BE) and plank (PL). Seven recreationally trained men (age: 28 ± 3.6 years, body mass: 92 ± 26.1 kg, height: 175 ± 5.3 cm, 3-RM front squat test: 125 ± 49.8 kg, 3-RM overhead squat test: 91 ± 15.5 kg) participated in this within-subject crossover design. Two isometric exercises (plank and Biering-Sorenson back extension) were also included for trunk musculature comparisons. Neuromuscular activitation of the vastus lateralis (VL), biceps femoris (BF), thoracic region of erector spinae (ES), middle trapezius (MT), rectus abdominis (RA), external oblique (EO), serratus anterior (SA), and anterior deltoid (AD). The neuromuscular activity of the FS and OHS were analyzed using a 2 X 3 (squat variation X intensity) repeated measures analysis of variance (ANOVA). Effects were further analyzed by Bonferroni corrected paired t-tests. Results showed that AD activity was significantly greater (p \u3c .05) during the FS compared to OHS at 65 and 95% of the 3-RM, while MT activity was significantly greater (p \u3c .05) during the OHS than the FS at 80 and 95% of the 3-RM. ES activity was significantly greater (p\u3c .05) during both the FS and OHS compared to the BE, but PL elicited significantly greater EO and RA activity than both the FS and OHS. These findings reveal that the FS and OHS can help facilitate the activation of muscles supporting the shoulder complex, scapula and lower back

Comparing Muscle Oxygenation and Maximal Blood Lactate Concentration in Middle-Distance Athletes: A Speed Reserve Ratio Analysis

Middle-distance running is a unique discipline that utilizes both aerobic and anaerobic abilities, resulting in a physiologically diverse athlete population. This diversity in athlete makeup underscores the necessity for precise physiological profiling methods to improve individualized training and race strategy approaches. While the Speed Reserve Ratio (SRR) has garnered attention as an accurate and effective tool in athlete profiling, skeletal muscle oxygenation (SmO2) and blood lactate also have shown potential in this field. However, the effectiveness of these biomarkers in middle-distance populations, especially in conjunction with SRR, is less understood. PURPOSE: This research aims to understand the relationships between SRR, changes in SmO2, and peak blood lactate concentrations in male middle-distance runners. By establishing correlations between these biomarkers, we aim to evaluate their potential to characterize an athlete\u27s aerobic and anaerobic capabilities, which could enhance personalized training and performance optimization. METHODS: Nine male middle-distance runners (age 22.89±2.62 years, weight 71.03±8.42 kg, height 172.03±9.24 cm) were evaluated in two distinct exercise tests. The initial test was a 50m sprint designed to determine max sprint speed (MSS). The subsequent test involved an incremental treadmill protocol that measured VO2 max, max aerobic speed (MAS), the change in SmO2 via a portable near-infrared spectroscopy (NIRS) device, and post-exercise peak blood lactate levels. Pearson correlation coefficients were used to analyze associations. RESULTS: Analysis revealed significant correlations between SRR and VO2max (r = -0.897, p = 0.009), SRR and changes in SmO2 (r = 0.698, p = 0.036), and between SmO2 and MSS (r = 0.756, p = 0.019). CONCLUSION: The correlations establish a strong link between SRR, VO2max, and SmO2 changes. The data suggests that measuring SmO2 can help predict a middle-distance runner’s aerobic and anaerobic capacities, emphasizing its potential as a pivotal biomarker for athlete profiling. Additionally, our findings bolster the SRR\u27s role as a tool for detailed physiological profiling, advocating for its application in athlete evaluation and tailored training recommendations

A 32 kb Critical Region Excluding Y402H in CFH Mediates Risk for Age-Related Macular Degeneration

Complement factor H shows very strong association with Age-related Macular Degeneration (AMD), and recent data suggest that multiple causal variants are associated with disease. To refine the location of the disease associated variants, we characterized in detail the structural variation at CFH and its paralogs, including two copy number polymorphisms (CNP), CNP147 and CNP148, and several rare deletions and duplications. Examination of 34 AMD-enriched extended families (N = 293) and AMD cases (White N = 4210 Indian = 134; Malay = 140) and controls (White N = 3229; Indian = 117; Malay = 2390) demonstrated that deletion CNP148 was protective against AMD, independent of SNPs at CFH. Regression analysis of seven common haplotypes showed three haplotypes, H1, H6 and H7, as conferring risk for AMD development. Being the most common haplotype H1 confers the greatest risk by increasing the odds of AMD by 2.75-fold (95% CI = [2.51, 3.01]; p = 8.31×10−109); Caucasian (H6) and Indian-specific (H7) recombinant haplotypes increase the odds of AMD by 1.85-fold (p = 3.52×10−9) and by 15.57-fold (P = 0.007), respectively. We identified a 32-kb region downstream of Y402H (rs1061170), shared by all three risk haplotypes, suggesting that this region may be critical for AMD development. Further analysis showed that two SNPs within the 32 kb block, rs1329428 and rs203687, optimally explain disease association. rs1329428 resides in 20 kb unique sequence block, but rs203687 resides in a 12 kb block that is 89% similar to a noncoding region contained in ΔCNP148. We conclude that causal variation in this region potentially encompasses both regulatory effects at single markers and copy number

Back Squat Potentiates Both Vertical and Horizontal Jump Performance in Collegiate Ice Hockey Players

Background: Back squats (BSQ) have been shown to transiently improve performance in explosive vertical movements such as the vertical jump (VJ). Still, understanding of this phenomenon, termed post-activation potentiation (PAP), remains nebulous as it relates to explosive horizontal movements. Objective: Therefore, the purpose of the present investigation was to assess whether heavy BSQ can potentiate both VJ and horizontal jump (HJ) performance. Method: Nine male ice hockey players from the Long Beach State ice hockey team performed five testing sessions separated by 96-hours. The first testing session consisted of a one repetition maximum (1-RM) BSQ to determine subsequent testing loads. The four subsequent testing sessions, which were randomized for order, consisted of five repetitions of BSQ at 87% 1-RM followed by horizontal jump (BSQ-HJ), five repetitions of BSQ at 87% 1-RM followed by vertical jump (BSQ-VJ), horizontal jump only (CT-HJ) and vertical jump only (CT-VJ). During the potentiated conditions, rest intervals were set at five minutes between the BSQ and either VJ or HJ. Alpha-level was set a priori at 0.05. Results: The results indicate that both vertical (p=0.017) and horizontal (p=0.003) jump were significantly increased (VJ= +5.51cm, HJ= +11.55cm) following a BSQ.  Conclusion: These findings suggest that BSQ may improve both vertical and horizontal jump performance in athletes who participate in sports emphasizing horizontal power, such as ice hockey

Kinetic and Kinematic Analysis of the Split Jerk and the Split Jerk from the Rack

The clean and jerk is one of the movements in the sport of weightlifting. Research has broken down the movement of the power clean and hang power clean, which is what seems to be primarily used in the field of strength and conditioning. However, by looking at the split jerk we could gain new insight into increasing power outputs in athletes by utilizing the split jerk in training. PURPOSE: Therefore, the purpose of this research is to analyze the power output and knee joint angles of the split jerk from two different positions, taken off the rack (SJ) and the split jerk lifted after the squat clean (C&J). METHODS: Five weightlifters who have competed in an USAW sanctioned weightlifting meet within the last 2 years, between 18-35 years, training 3-5 days a week and had no previous injuries within the last 6-months participated. After performing the specific warm-up, markers were placed on the athletes. The athletes then began to warm up to their working weight at 80% of 1RM by gradually performing 1 rep of their clean & jerk at 55%, 60%, 65%, 75% of their 1RM. Once the athlete had warmed up, four trials were recorded for the full clean & jerk and split jerk from the rack. The order of the movements was randomly selected for each athlete. Sagittal knee joint angles and peak power were assessed for each movement. RESULTS: When comparing the joint angles of the split jerk taken off the rack to the split jerk lifted after the squat clean, average peak knee flexion and average peak knee extension were similar when comparing within subjects. Average peak knee flexion for the C&J and SJ were -70.09 (+/- 12.56) degrees, and -70.70(+/-10.60) degrees, respectively, with a 0.006% difference. Average peak knee extension for both the C&J and SJ were -6.01(+/-9.40) degrees, and -6.05(+/-10.36) degrees, respectively, with a 0.0004% difference. Average peak power outputs for the C&J and SJ were 932.30(+/-278.85) watts, and 963.24(+/-267.64) watts, respectively, with a 0.31% difference between the groups. CONCLUSION: In conclusion the split jerk taken from the rack had a slightly greater peak power output than the split jerk performed after the clean. Interestingly, average peak knee extension values do not dictate an increase in power outputs. More research needs to be done to determine if average peak knee flexion values could determine a higher power