The use endocrine markers to predict and monitor performance in strengh [sic] and power activities

Hormones are typically considered to be chemical messengers, which are designed to be released from specific cells where they are carried to their target tissues for binding to receptors. It is this binding of a hormone molecule to its specific receptor which allows for an action to occur (Hadley and Levine 2006). Testosterone is the predominant androgen in the majority of mammalian species and is largely responsible for regulation of reproduction and maintenance of sexual function. In addition, in adult mammals, T has multiple other roles including the growth of muscle and bone, hematopoesis, blood coagulation, development and regulation of plasma lipids, protein and carbohydrate metabolism, and cognitive function (Bhasin, 2005). Cortisol has typically been thought of as a suppressor of the immune system and an anti-inflammatory agent as it is an inducer of cellular apoptosis. In research where corticosteroids were given intravenously to humans, responses of apoptosis of T and B cells were noted (Cohen and Duke 1984). Testosterone and C as well as other hormones have received significant attention in recent years by several researchers who have proposed a link between these hormones and performance, adaptive capability, and overtraining syndrome (Kraemer & Ratamass, 2005). The use of T to C ratio (T/C) has gained some popularity in recent years as a method to monitor anabolic/catabolic state in athletes, and to predict athletic performance and/or overtraining. There is a growing body of evidence that T/C may be useful in monitoring training stress and physiological phenomenon, however, the relationship between these variables and any actual physical performance has not been solidly established at this time

The relationship between isometric and dynamic strength in college football players

Previous research has demonstrated the importance of both dynamic and isometric maximal strength and rate of force development (RFD) in athletic populations. The purpose of this study was to examine the relationships between measures of isometric force (PF), RFD, jump performance and strength in collegiate football athletes. The subjects in this study were twenty-two men [(mean ± SD):age 18.4 ± 0.7 years; height 1.88 ± 0.07 m; mass 107.6 ± 22.9 kg] who were Division I college football players. They were tested for PF using the isometric mid thigh pull exercise. Explosive strength was measured as RFD from the isometric force-time curve. The one repetition maximum (1RM) for the squat, bench press and power clean exercises were determined as measures of dynamic strength. The two repetition maximum (2RM) for the split jerk was also determined. Vertical jump height and broad jump was measured to provide an indication of explosive muscular power. There were strong to very strong correlations between measures of PF and 1RM (r = 0. 61 - 0.72, p \u3c 0.05). The correlations were very strong between the power clean 1RM and squat 1RM (r = 0.90, p \u3c 0.05). There were very strong correlations between 2RM split jerk and clean 1RM (r = 0.71, p \u3c 0.05), squat 1RM (r = 0.71, p \u3c 0.05), bench 1RM (r = 0.70, p \u3c 0.05) and PF (r = 0.72, p \u3c 0.05). There were no significant correlations with RFD. The isometric mid thigh pull test does correlate well with 1RM testing in college football players. RFD does not appear to correlate as well with other measures. The isometric mid thigh pull provides an efficient method for assessing isometric strength in athletes. This measure also provides a strong indication of dynamic performance in this population

Effectiveness of Blood Flow Restriction Training on Isokinetic Muscle Strength of the Quadriceps

Blood flow restriction (BFR) training has proven to be an effective method of producing muscle hypertrophy and increased strength, but the most efficacious percentage of blood flow occlusion while performing aerobic training is unclear. PURPOSE: To examine the effectiveness of BFR training while using two different cuff pressures on the strength of the quadriceps muscle group after three weeks of cycling training for fifteen-minute sessions performed three times per week. METHODS: Ten healthy participants (4 female, 6 male, 26 ± 3 years) were randomly assigned to one of two groups: BFR with 60% occlusion applied to the right quadricep or BFR with 80% occlusion applied to the right quadricep. The training protocol consisted of cycling on a stationary ergometer for 15 minutes at 70 RPM with 25 watts of resistance, with the BFR cuff inflated to their assigned occlusion percentage, performed three times a week for three weeks. Muscle strength of the quadriceps was measured bilaterally at baseline and at three weeks using an isokinetic dynamometer at speeds of 60, 180, and 300 degrees per second using a standardized knee extension protocol. Given the normally distributed data for torque and work of the knee extensors, a 2 x 2 (group by time) ANOVA was used to perform between and within-group comparisons. Statistical significance was at an alpha of 0.05 for all analyses. RESULTS: The ANOVA revealed no between group differences but statistically significant changes within time for torque at 180 (p\u3c.001) and 300 (p=0.01) degrees per seconds. Work at 180 and 300 degrees per seconds were also statistically significant (p\u3c.001 and .013, respectively) across time. CONCLUSION: It appears there are no differences between the two different BFR occlusion pressures between groups, indicating both occlusion pressures elicit similar gains in quadriceps strength over a three-week training period. However, it seems both groups displayed improved torque and work at higher speeds, indicating that BFR training in this manner and protocol provides more of a benefit in increasing muscular endurance, opposed to strength itself

Effectiveness of Blood Flow Restriction Training on Aerobic Performance During Cycling Exercise in Healthy Adults

Blood flow restriction (BFR) has emerged as an alternate rehabilitation modality, intending to enhance muscular strength, hypertrophy, metabolic response, and functional outcomes in various populations. However, there is a lack of research evidence on the efficacy of BFR during aerobic exercise. PURPOSE: To compare aerobic capacity following a cycling protocol with BFR at 60% (BFR-60) 80% (BFR-80) occlusion. METHODS: Ten healthy participants (26 ± 3.0 years; 6 males; 4 females) were randomly assigned to either: BFR-60 or BFR-80. Aerobic Capacity was measured at baseline, and three weeks during a sub-maximal stationary cycle ergometer protocol connected to a metabolic analyzer for the assessment of peak oxygen consumption (VO2 peak). Aerobic testing consisted of performing the YMCA protocol which consisted of pedaling at 70 rev/min with a load of 25-watts. Heart Rate (HR) was monitored continuously at the end of the first 3 minutes and used to determine the load increase. Subjects cycled for 15 minutes at which point a 25-watt increase occurred every 3 minutes until the participant reached one or more of the following criteria: 80% of their predicted HR (T80) using the HR reserve formula, an RER \u3e 1.0, or a leveling of the oxygen curve. BFR cuffs were applied between baseline and 3-week reassessment of aerobic capacity at the appropriate level of occlusion and a cycling protocol was performed (15 minutes; 3 d/wk.). Given the small sample size and the non-normal data distribution for the variable of T80, a Mann-Whitney and Wilcoxon tests were used to evaluate between and within (time) groups differences, respectively. For the between-group comparison, a composite score for T80 based on the pre-post difference was calculated for both groups. Then this calculated difference was used to compare both groups. Peak VO2 was normally distributed, therefore, a 2x2 (group by time) ANOVA was used to perform between and within-group comparisons. Statistical significance was at an alpha of 0.05 for all analyses. RESULTS: The between group comparisons of the T80 was not statistically significant. The within group comparison for T80 for the BFR-60 group approached significance (p = 0.08) while the BFR-80 group was not significant (p = 0.89). The within time ANOVA approached significance (p = 0.09) while there were no between group differences (p = 0.99). CONCLUSION: Aerobic performance over time was seen to improve primarily in the 60% occlusion BFR group. The sample size or short intervention duration might have affected the effectiveness of this intervention

The Relationship Between Aerobic and Anaerobic Performance in Recreational Runners

International Journal of Exercise Science 9(5): 625-634, 2016. Research has indicated that combined aerobic and anaerobic training (concurrent training) may improve aerobic performance greater than aerobic training alone. The purpose of this investigation was to establish any associations between aerobic and anaerobic performance. Eleven participants (n = 11, age = 34.1 ± 13 years, VO2max = 58.4 ± 7.8) volunteered for this study. Participants were asked for endurance training experience (4.7 ± 3.7 years) and resistance training experience (4.1 ± 4.6 years). To meet training status, participants were to have a VO2max in the 80th percentile as per ACSM guidelines. The Bruce treadmill test was used to measure aerobic performance. In order to measure anaerobic performance, several tests were completed utilizing a force platform. A Pearson Product R Correlation Coefficient was calculated to determine correlations between variables. The results show significant correlation between VO2max and RFD (r = 0.68). Further analyses utilizing Cohen’s effect size indicated a strong association between VO2max and peak force, as well as running efficiency and peak power, relative peak power, and power endurance. These results indicate an existing possibility that anaerobic performance measures such as RFD may have a positive relationship with aerobic performance measures such as VO2max. Therefore, it may be beneficial to integrate specific training components which focus on improving RFD as a method of improving running performance

Joint Range of Motion is Associated With Injury Risk in Women\u27s Collegiate Soccer Players

Range of motion as a predictor for injury in athletic population is controversial. Despite this, it is common to see strategies to improve ROM included in strength and conditioning, rehabilitation, and on-field warm up protocols. PURPOSE: The purpose of this investigation was to assess relationships, which may exist between joint-specific ROM and injury rates, throughout a women’s NCAA Division II collegiate soccer season. METHODS: Twenty-eight women (age 19.7 + 1.6 years, height 1.6 + .5 m, mass 63.4 + 7.9 kg) were assessed using a battery of ROM tests prior to a competitive season. Injury rates, types, and time lost from participation were tracked throughout the season. Injury information was coded and categorized each week in the following: acute vs. chronic, soft tissue vs. hard tissue; upper vs. lower body; specific anatomical location; contact vs. non-contact; week of injury occurrence; practice days missed from injury; and games missed from injury. Association was measured via a Spearman’s rank correlation coefficient, and a stepwise linear regression was performed for any variables which showed significant correlation to determine predictive relationship, which may exist. ROM was evaluated independently by multiple rater and inter-rater reliability was high (ICC = 0.995, 95% CI upper and lower = 0.996-0.995, p=0.000). Statistical significance was set a priori at p \u3c 0.05. RESULTS: Tests of hip extension and external rotation (ER); knee flexion and extension; and ankle plantarflexion (PF), dorsiflexion (DF), and inversion showed moderate to strong correlation with injury (range r = 0.48-0.72). Prediction equations were developed for ankle dorsiflexion (Y=2.6-0.45(X), p=0.002); left thoracolumbar rotation (Y=2.45-0.2(X), p=0.002); left hip ER (Y=0.86-0.75(X), p=0.02); and left ankle PF (Y=1.89-0.03(X), p=0.02) CONCLUSION: The main finding of this investigation is that multiple assessments of ROM showed association with subsequent injury in women’s collegiate soccer players. While previous research on this has been less supportive, it is possible that there is a range which is appropriate for this population below which rate of injury may increase. Future investigations may wish to explore this relationship, to include potential mechanisms which may be influential in addition, while relationships between ROM and injury were not joint specific, it is possible that there are relationships of regional interdependence that may exist

Joint Laxity is Predictive of Injury in Women’s Collegiate Soccer Players

Joint laxity assessment has been purported to be a valid and reliable screening tool for injury prediction in multiple populations. PURPOSE: The purpose of this investigation was to assess relationships which may exist between joint laxity and injury rates throughout a women’s NCAA Division II Collegiate Soccer season. METHODS: Twenty-eight women (age 19.7±1.6 yrs, height 1.6±0.5 m, mass 63.4±7.9 kg) were assessed using the Lachman, anterior drawer of the ankle, medial and lateral talar tilt, and Thessaly’s tests prior to a competitive season. Injury rates, types, and time lost from participation were tracked throughout the season. Injury information was coded and categorized each week in the following: acute vs. chronic; soft vs. hard tissue; upper vs. lower body; specific anatomical location; contact vs. non-contact; week of injury occurrence; practice days missed from injury; and games missed from injury. Association was measured via a Spearman\u27s rank correlation coefficient and a stepwise linear regression was performed for any variables which showed significant correlation to determine predictive relationships which may exist. Joint laxity tests were evaluated independently by multiple raters and inter-rater reliability was high (Cohen’s Kappa = 0.901-1.0, p=0.001). Statistical significance was set a priori at p≤0.05. RESULTS: Significant correlation and prediction were observed between joint laxity as assessed via the anterior drawer of the ankle test and injury (r=0.57, p≤0.05; Y=2.6-0.80(X), p=0.001). CONCLUSION: The main finding of this investigation is that joint laxity as assessed via the anterior drawer of the ankle test was associated with joint and ligament injuries in women’s collegiate soccer athletes through the course of a competitive season. Additional investigations should explore mechanisms behind this relationship. In addition, sports medicine professionals and coaches may wish to consider the use of this test as a potential screening tool for injury risk as well as interventions to enhance joint stability for athletes who are suspected of being positive on this test

Change of Direction is Associated with Non-Contact Injuries in Women\u27s Collegiate Soccer Players

Injury rates have been reported between men and women soccer athletes. PURPOSE: The purpose of this investigations was to assess relationships which may exist between performance in a change of direction (COD) test and injury rates throughout a women’s NCAA Division II Collegiate Soccer season. METHODS: Twenty-eight women (age 19.9±1.6 yrs, height 1.6±0.5 m, mass 63.4±7.9 kg) were assessed using the Soccer Specific Agility test prior to a competitive season. Injury rates, types, and time lost from participation were tracked throughout the season. Injury information was coded and categorized each week in the following: acute vs. chronic; soft vs. hard tissue; upper vs. lower body; specific anatomical location; contact vs. non-contact; week of injury occurrence; practice days missed from injury; and games missed from injury. Association was measured via a Spearman\u27s rank correlation coefficient and a stepwise linear regression was performed for any variables which showed significant correlation to determine predictive relationships which may exist. Statistical significance was set a priori at p≤0.05. RESULTS: Soccer Specific Agility times were 7.04±0.36 sec. A moderate correlation was seen between agility performance and non-contact injuries (r=0.47, p≤0.05). DISCUSSION: The main finding of this investigation is that performance on the soccer specific agility test showed association with non-contact injury rates throughout a women’s collegiate soccer season, with lower time being associated with smaller injury rates. Future investigations should attempt to explore whether improvements in COD, which may be assessed using the SSA, can lead to meaningful reductions in injury rates. Sports medicine professionals and coaches may wish to adopt strategies to improve COD in an effort to reduce rates of non-contact injuries in their athletes

The Relationship Between Landing Mechanics and Injury Risk in Women\u27s Collegiate Soccer Players

Mechanical performance in landing related tasks has been suggested to be related to injury in athletic. PURPOSE: The purpose of this investigations was to assess relationships which may exist between performance in landing mechanics and injury rates throughout a women’s NCAA Division II Collegiate Soccer season. METHODS: Twenty-eight women (age 19.7±1.6 yrs, height 1.6±0.5 m, mass 63.4±7.9 kg) were assessed using the Landing Error Scoring System (LESS) test prior to a competitive season. Injury rates, types, and time lost from participation were tracked throughout the season. Injury information was coded and categorized each week in the following: acute vs. chronic; soft vs. hard tissue; upper vs. lower body; specific anatomical location; contact vs. non-contact; week of injury occurrence; practice days missed from injury; and games missed from injury. Association was measured via a Spearman\u27s rank correlation coefficient and a stepwise linear regression was performed for any variables which showed significant correlation to determine predictive relationships which may exist. The LESS test was evaluated independently by multiple raters and inter-rater reliability was high (ICC=0.824, 95% CI upper and lower = 0.917-0.657, p=0.001). Statistical significance was set a priori at p≤0.05. RESULTS: No significant correlations were determined between LESS test performance and injury and the LESS score did not add strength of association to any predictive variables. DISCUSSION: The main finding of this investigation is that performance on the LESS test did not show significant association with injury rates in women’s collegiate soccer players. LESS test performance has previously been suggested to be a valid and reliable clinical assessment tool, and claims have been made regarding its utility as a screening tool for identification of persons who may be at risk for subsequent injury. Landing mechanics may still be a valid predictor of injury risk. However, the results of our investigation do not support the use of the LESS test as a screening tool for injury risk in women’s collegiate soccer athletes

African linguistics on the prairie: Selected papers from the 45th Annual Conference on African Linguistics

African Linguistics on the Prairie features select revised peer-reviewed papers from the 45th Annual Conference on African Linguistics, held at the University of Kansas. The articles in this volume reflect the enormous diversity of African languages, as they focus on languages from all of the major African language phyla.  The articles here also reflect the many different research perspectives that frame the work of linguists in the Association for Contemporary African Linguistics. The diversity of views presented in this volume are thus indicative of the vitality of current African linguistics research. The work presented in this volume represents both descriptive and theoretical methodologies and covers fields ranging from phonetics, phonology, morphology, typology, syntax, and semantics to sociolinguistics, discourse analysis, language acquisition, computational linguistics and beyond.  This broad scope and the quality of the articles contained within holds out the promise of continued advancement in linguistic research on African languages