Influence of Sport Specialization on Athletic Performance and Injury Risk in Collegiate Swimmers

To assess the effect of swimming specialization on performance and injury risk in collegiate swimmers, thirty collegiate swimmers (20.1 ± 0.9 years [18.5 – 22.3 years]) were asked to complete an anonymous survey to provide information regarding their sports participation history, success in swimming, and the occurrence and quantity of swimming-related injuries. Specialization status was determined by the swimmer claiming they had specialized and by the number of months (≥ 8 months) they participated in swimming each year. Correlation analysis revealed several significant (p \u3c 0.05) relationships between all determinants of specialization, swimming success, and swimming injuries. Stepwise regression analysis revealed that the age which an athlete specialized was the best predictor of the occurrence of a swimming- related injury (R2 = 0.34, p = 0.004) and the number of injuries sustained (R2 = 0.25, p = 0.019). Years of competitive swimming experience was the best predictor (p \u3c 0.008) of performance in the freestyle stroke at 50-yards (R2 = 0.47), 100-yards (R2 = 0.53), and 500-yards (R2 = 0.43), the back stroke at 200-yards (R2 = 0.41), and the 100-yard butterfly (R2 = 0.55). The age in which the athlete specialized in swimming was the best predictor of the 200-yard individual medley (R2 = 0.30, p = 0.037). Our data suggests that swimming specialization may be beneficial for success in select swimming events but is not as important as years of competitive experience and may also lead to a greater number of swimming-related injuries

The effect of chronic quercetin supplementation on bone health in postmenopausal women: A double-blind placebo-controlled investigation

Currently, there is limited research investigating the effects of quercetin on bone turnover and density. Therefore, this study aimed to examine the efficacy of 90-day quercetin supplementation on bone turnover, inflammation, body composition, and physical function in postmenopausal women. Thirty-four healthy postmenopausal women (59.2 ± 7.0 yrs, 80.7 ± 15.6 kg, 29.8 ± 6.1 kg⸱m2) participated in the double-blind placebo-controlled investigation. Participants were randomly assigned to one of two groups: 500 mg of Q or 500 mg of fiber (placebo; PLB). Data collected during the pre-and post-supplementation assessments included: bone turnover (osteocalcin, P1NP, CTX), inflammation markers (IL-6, TNF-alpha, CRP), body composition, dominant handgrip strength, and timed up and go test. Independent samples t-tests were used for between-group comparisons of baseline values and the percent change for each dependent variable. A significant difference in percent change for osteocalcin (Q: 20.5±25.7; PLB: 1.3±17.2; p=0.016; d=0.89), P1NP (Q: 28.9 (6.0–57.3); PLB: 4.6 (-7.6 – 8.5); p=0.030; d=0.64), and CTX (Q: 39.0 (-10.0 – 84.6); PLB: -7.74 (-28.9 – 18.5); p=0.023; d=0.91) was found between Q and PLB, with greater increases in Q. Changes in the inflammation markers IL-6 (Q: -17.6±24.1; PLB: 2.90±31.1; p=0.045; d=0.73) and TNF-alpha (Q: -4.9± (-15.3 – [-3.2]); PLB: 1.9 (-7.8 – 4.0); p=0.021; d=0.90) between the two groups were significant. No significant changes were found between groups for CRP, body composition, and physical function (p\u3e0.05). The data suggest that Q may improve bone health status in postmenopausal women through its ability to decrease pro-inflammatory mediators and increase turnover markers

The Effect of Quercetin on Bone Turnover Markers, Inflammatory Markers, and Bone Mineral Density in Postmenopausal Women: A Double-Blind Placebo-Controlled Investigation

Maintaining optimal bone health prevents major bone disorders (e.g., osteoporosis) and prolongs longevity. Quercetin is a plant-based flavonoid that is suggested to have anti-inflammatory effects and may improve bone health. PURPOSE: To investigate the effects of quercetin supplementation over 90-days on prominent bone turnover markers (BTMs), inflammatory markers, bone mineral density (BMD), body composition, and physical functioning in postmenopausal women. METHODS: Thirty-three healthy, nonosteoporotic, postmenopausal women (59.2±7.0 years) participated in a double-blind, placebo-controlled investigation. Participants were randomized into one of two supplement groups: 1) 500 mg of quercetin (QUE) once daily or 2) 500 mg of methylcellulose (placebo; PLB) once daily. Pre- and post-testing visits included assessments of BTMs (i.e., osteocalcin [OC], procollagen type-I N-terminal propeptide [PINP], and type-I collagen cross-linked C-terminal telopeptide [CTX]), inflammatory markers (i.e., interleukin [IL]-6, tumor necrosis factor-alpha [TNF-a], and C-reactive protein [CRP]), BMD measurements, body composition measurements (i.e., body fat percentage), and physical function. RESULTS: The QUE group increased OC (p=0.016; d=0.89), PINP (p=0.030; d=0.64), and CTX (p=0.023; d=0.91) levels and decreased IL-6 (p=0.045; d=0.73) and TNF-a (p=0.021; d=0.90) levels compared to PLB. CRP (p=0.448; d=0.34), BMD, body composition, and physical function remained unchanged. CONCLUSION: The results indicate that QUE may maintain optimal bone health by mediating bone formation and decreasing pro-inflammatory cytokines

Sex Differences in Plantar Flexor Strength and Contractile Properties after Isometric and Dynamic Fatigue

Purpose: To determine sex differences in strength and contractile properties after isometric and dynamic fatiguing exercise of the plantar flexors. Methods: Recreationally active males (n=13, age=22.4±2.2 yrs) and females (n=15, age=20.9±2.4 yrs) performed a maximal isometric (2 min) and isotonic (120 reps at 30% peak torque) fatigue task on 2 separate visits. Before and after each fatigue task, participants performed a 3 sec maximal voluntary isometric contraction (MVIC) with tibial nerve stimulation being delivered during and immediately after the MVIC. Peak torque (PT; highest 250 ms) was obtained during the voluntary phase of the MVIC. Peak twitch torque (TTQ), rate of torque development (RTD; Δtorque/Δtime), and half relaxation time (HRT; time for TTQto decrease from peak to 50%) were calculated from the resting twitch after the MVIC. Voluntary activation (VA%; ability of the muscle to be fully activated) was calculated using a corrected interpolated twitch formula. Three-way (condition × sex × time) repeated measures ANOVAs were used for analysis. Results: Regardless of sex or condition, TTQ(-23.1%), RTD (-12.6%), HRT (+22.9%) were changed after fatigue (p\u3c0.05), while VA% remained unchanged (p\u3e0.05). Regardless of condition, PT was more reduced in males (-22.5%) compared to females (-19.2%)(p=0.017). Conclusions: Our findings indicate that the fatigue-induced decrease in strength was greater in males than females. While our findings do not identify the contributing physiological mechanism(s), changes at the peripheral level may be responsible

Effects of plyometric- and cycle-based high-intensity interval training on body composition, aerobic capacity, and muscle function in young females: a field-based group fitness assessment

High-intensity interval training (HIIT) is an effective alternative to moderate intensity continuous training for improvements in body composition and aerobic capacity; however, there is little work comparing different modalities of HIIT. The purpose of this study was to compare the effects of plyometric- (PLYO) and cycle-oriented (CYC) HIIT on body composition, aerobic capacity, and skeletal muscle size, quality, and function in recreationally trained females. Young (21.7 ± 3.1 yrs), recreationally active females were quasi-randomized (1:1 ratio) to 8 weeks of twice weekly PLYO (n = 15) or CYC (n = 15) HIIT. Body composition (four-compartment model), VO2peak, countermovement jump performance, muscle size, and echo intensity (muscle quality), as well as strength and power of the knee extensors and plantar flexors were measured before and after training. Both groups showed a similar decrease in body fat percentage (p \u3c 0.001; = 0.409) and echo intensity (p \u3c 0.001; = 0.558), and an increase in fat-free mass (p \u3c 0.001; = 0.367) and VO2peak (p = 0.001; = 0.318). Muscle size was unaffected (p \u3e 0.05), whereas peak torque was reduced similarly in both groups (p = 0.017; = 0.188) and rapid torque capacity was diminished only for the knee extensors after CYC (p = 0.022; d = −0.67). These results suggest that PLYO and CYC HIIT are similarly effective for improving body composition, aerobic capacity, and muscle quality, whereas muscle function may express moderate decrements in recreationally active females. ClinicalTrials.gov (NCT05821504

Identifying an indoor air exposure limit for formaldehyde considering both irritation and cancer hazards

Formaldehyde is a well-studied chemical and effects from inhalation exposures have been extensively characterized in numerous controlled studies with human volunteers, including asthmatics and other sensitive individuals, which provide a rich database on exposure concentrations that can reliably produce the symptoms of sensory irritation. Although individuals can differ in their sensitivity to odor and eye irritation, the majority of authoritative reviews of the formaldehyde literature have concluded that an air concentration of 0.3 ppm will provide protection from eye irritation for virtually everyone. A weight of evidence-based formaldehyde exposure limit of 0.1 ppm (100 ppb) is recommended as an indoor air level for all individuals for odor detection and sensory irritation. It has recently been suggested by the International Agency for Research on Cancer (IARC), the National Toxicology Program (NTP), and the US Environmental Protection Agency (US EPA) that formaldehyde is causally associated with nasopharyngeal cancer (NPC) and leukemia. This has led US EPA to conclude that irritation is not the most sensitive toxic endpoint and that carcinogenicity should dictate how to establish exposure limits for formaldehyde. In this review, a number of lines of reasoning and substantial scientific evidence are described and discussed, which leads to a conclusion that neither point of contact nor systemic effects of any type, including NPC or leukemia, are causally associated with exposure to formaldehyde. This conclusion supports the view that the equivocal epidemiology studies that suggest otherwise are almost certainly flawed by identified or yet to be unidentified confounding variables. Thus, this assessment concludes that a formaldehyde indoor air limit of 0.1 ppm should protect even particularly susceptible individuals from both irritation effects and any potential cancer hazard

Contractile Parameters Of The Knee Extensors In Young, Middle-aged, And Older Males

Peak power (PP) is decreased in older adults; however, less is clear regarding the determinants of PP, contractile torque and velocity. Furthermore, it is unknown if these measures are affected differently in middle and old age. PURPOSE: To compare PP and its determinants for the knee extensors in young, middle-aged, and older males. METHODS: As part of a larger ongoing investigation, contractile properties of the knee extensors were assessed in healthy, untrained young (YM: n = 8, age = 20.5 ± 1.6 yrs),middle-aged (MM: n = 6, age = 46.0 ± 2.9 yrs) and older (OM: n= 6, age = 69.0 ± 3.10 yrs) males using a Biodex System 4 dynamometer. Upon completing a familiarization visit, a testing visit involving three maximal voluntary isotonic knee extensions, performed at 40% of isometric peak torque, was completed. Participants were instructed to “kick out as hard and fast as possible” prior to each contraction. Power was calculated as the product of torque and velocity for the isotonic contractions using custom written software and PP was recorded. In addition, velocity (VEL) and torque (TQ), at the moment in time PP occurred, were recorded. One-way analyses of variance and Games-Howell post hoc tests were used to compare groups. RESULTS: PP was lower in OM compared to YM (50%; p = 0.021), but was similar in MM compared to YM and OM (p \u3e 0.05). VELwas decreased in OM compared to YM (36%; p = 0.007) and MM (24%; p = 0.044), however, no difference was noted between MM and YM. TQ was similar between groups (p = 0.147). CONCLUSION: Our preliminary data indicate that reductions in VEL for the knee extensors occur between middle and old age prior to a decrease in PP, while TQ is maintained in old age. Thus, VEL appears to be more dramatically affected by age, and the age-related decrease in PP may be primarily mediated by impaired velocity capacity

Age Does Not Attenuate Maximal Velocity Adaptations in the Ipsilateral and Contralateral Limbs During Unilateral Resistance Training

This study examined the effects of unilateral resistance training (RT) on maximal velocity parameters in the ipsilateral and contralateral legs in young and older males. Young (n = 22; age = 21.55 ± 2.23 years) and older (n = 20; age = 65.10 ± 9.65 years) males were assigned to training or control groups. Unilateral isokinetic RT of the knee extensors was performed for 4 weeks. Peak velocity and acceleration were identified during a dynamic maximal voluntary contraction before (PRE), at Week 2 (MID), and after Week 4 (POST) of RT. Age-independent increases in peak velocity (1.5%) and acceleration (4.5%) were demonstrated at POST for the trained leg. For the untrained leg, acceleration increased (4.3%) at POST similarly between training groups. These findings provide evidence for the high degree of neuromuscular plasticity, regardless of age, during the early phase of RT, and the potential for cross education of acceleration

Cross-education: effects of age on rapid and maximal voluntary contractile characteristics in males

Purpose The purpose of this study was to determine the effect of age on the cross-education of rapid and maximal contractile properties for the knee extensors. Methods Young (n = 10; age = 21.1 ± 1.7 years) and older (n = 10; age = 65.3 ± 8.3 years) males performed unilateral isokinetic resistance training (RT) of the knee extensors for 4 weeks. Maximal voluntary isokinetic (45° s−1 and 300° s−1) and isometric testing was conducted for the trained and untrained leg before and after RT. Peak torque (PT) and acceleration were obtained from isokinetic testing as well as torque at 30 ms (TQ30) and 100 ms (TQ100) from the 45° s−1 contraction. PT and rate of torque development were recorded from the isometric contractions. Results Independent of age, isometric PT (10.1%; p = 0.006) as well as PT and acceleration at 300° s−1 (6.7%; p = 0.008 and 4.0%; p = 0.016, respectively) increased in the untrained leg. At 45° s−1, acceleration was increased (3.6%; p = 0.021), but PT remained unchanged (p = 0.227). TQ100 increased similarly between groups (4.5%; p = 0.014), but TQ30 increased only in the older group (9.5%; p = 0.022). Conclusions Cross-education of rapid and maximal contractile parameters can be achieved early during unilateral RT independent of age. These findings indicate the potential for particular unilateral RT protocols to be used for older adults in rehabilitative settings to offset disuse-related reductions in contractile function, which are most dramatic in this population

The addition of β-Hydroxy β-Methylbutyrate (HMB) to creatine monohydrate supplementation does not improve anthropometric and performance maintenance across a collegiate rugby season

© 2020 The Author(s). Background: Muscular damage sustained while playing rugby may hinder performance across a season. β-Hydroxy β-Methylbutyrate (HMB) may help attenuate muscle damage and maintain lean mass and performance. This study sought to determine the effect of combining HMB with creatine monohydrate supplementation on measures of stress and muscle damage, body composition, strength and sprinting kinetics throughout a rugby season. Methods: This double-blind, cross-over investigation recruited 16 male collegiate rugby players to provide resting blood samples and complete assessments of body composition, strength and sprinting performance prior to their fall season (PREFALL). After testing, the athletes were matched for fat-free mass and assigned to consume one of two supplementation regimens for 6 weeks: 5 g HMB + 5 g creatine per day (HMB-Cr: 20.9 ± 1.1 years; 177 ± 2 cm; 88.4 ± 4.9 kg) or 5 g creatine + 5 g placebo per day (Cr: 21.4 ± 2.1 years; 179 ± 2 cm; 88.3 ± 4.9 kg). After 6 weeks (POSTFALL), PREFALL testing was repeated in 13 of the original 16 athletes before a 10-wk wash-out period. Athletes who returned for the spring season (n = 8) repeated all fall-season procedures and testing prior to (PRESPRING) and following (POSTSPRING) their 6-wk spring season, except they were assigned to the opposite supplementation regimen. Results: Linear mixed models with repeated measures revealed group x time interactions (p \u3c 0.05) for observed for several measures but did not consistently and positively favor one group. During the fall season, knee extensor peak torque was reduced by 40.7 ± 28.1 Nm (p = 0.035) for HMB-Cr but remained consistent for Cr, and no group differences or changes were noted in the spring. In the spring, greater knee flexor rate of torque development (~ 149 Nm·sec- 1, p = 0.003) and impulse (~ 4.5 Nm·sec, p = 0.022) were observed in Cr at PRESPRING but not at POSTSPRING. Although significant interactions were found for cortisol concentrations, vastus lateralis pennation angle, and sprinting force, post-hoc analysis only revealed differences between fall and spring seasons. No other differences were observed. Conclusions: The combination of HMB and creatine monohydrate supplementation does not provide a greater ergogenic benefit compared to creatine monohydrate supplementation alone. Body composition, strength, and sprinting ability did not change across the season with creatine monohydrate supplementation