Impact of Muscle Material Properties on the Hypertrophic Response of Aged Women to Resistance Exercise

All of the reports that comprise this dissertation center around the overarching hypothesis that the attenuated response to resistance exercise observed in older adults is caused by an impaired ability of the muscle to sense mechanical stimuli as a result of increased muscle stiffness. In the first study we investigated the difference in the response of young and aged women to a single bout of resistance exercise. We hypothesized that there would be a less robust hypertrophic response to the exercise bout in the older adults than the young adults. The results of this study showed that young and aged women have a different response to acute exercise. The aged women had an attenuated response when compared to their young counterparts. It was also found that p70S6k phosphorylation is a robust marker that can be used to quantify hypertrophic response to acute resistance exercise. In the second study we investigated the impact of a long-term stretching intervention on the response of aged women to an acute bout of resistance exercise. The stretching was used as a means to modulate muscle stiffness to test they hypothesis that stiffness is related to hypertrophic response to exercise. The results of this study showed that stretching did improve response to an acute bout of resistance exercise. However, while there was a trend toward a reduction in muscle stiffness the change in muscle material properties was not significant. In the third study we investigated the impact of a long-term stretching intervention on the hypertrophic response of aged women to a long-term resistance exercise intervention. We hypothesized that having older women participate in a stretching intervention prior to beginning a resistance training intervention would improve their response to the resistance training program. The results of this study showed that performing a stretching intervention prior to beginning a resistance exercise intervention improved the hypertrophic response to resistance exercise. Taken together, these studies indicate that stretching does appear to be an effective means to improve response to both an acute bout of exercise and a long-term resistance exercise intervention

Impact of Muscle Material Properties on the Hypertrophic Response of Aged Women to Resistance Exercise

All of the reports that comprise this dissertation center around the overarching hypothesis that the attenuated response to resistance exercise observed in older adults is caused by an impaired ability of the muscle to sense mechanical stimuli as a result of increased muscle stiffness. In the first study we investigated the difference in the response of young and aged women to a single bout of resistance exercise. We hypothesized that there would be a less robust hypertrophic response to the exercise bout in the older adults than the young adults. The results of this study showed that young and aged women have a different response to acute exercise. The aged women had an attenuated response when compared to their young counterparts. It was also found that p70S6k phosphorylation is a robust marker that can be used to quantify hypertrophic response to acute resistance exercise. In the second study we investigated the impact of a long-term stretching intervention on the response of aged women to an acute bout of resistance exercise. The stretching was used as a means to modulate muscle stiffness to test they hypothesis that stiffness is related to hypertrophic response to exercise. The results of this study showed that stretching did improve response to an acute bout of resistance exercise. However, while there was a trend toward a reduction in muscle stiffness the change in muscle material properties was not significant. In the third study we investigated the impact of a long-term stretching intervention on the hypertrophic response of aged women to a long-term resistance exercise intervention. We hypothesized that having older women participate in a stretching intervention prior to beginning a resistance training intervention would improve their response to the resistance training program. The results of this study showed that performing a stretching intervention prior to beginning a resistance exercise intervention improved the hypertrophic response to resistance exercise. Taken together, these studies indicate that stretching does appear to be an effective means to improve response to both an acute bout of exercise and a long-term resistance exercise intervention

Practice day may be unnecessary prior to testing knee extensor strength in young healthy adults

A practice session is common prior to strength testing. However, the benefits of practice have not been previously reported. The purpose of this study was to determine the effect of a practice session on peak torque, mean torque and between trial variability across three test days. We hypothesized that peak and mean torque would be higher and less variable the second and third test days than the first. Twenty-five healthy, young participants completed 3 maximal voluntary isometric and isokinetic knee extensions on three separate days. No difference in isometric torque was found between days 1 and 2, but there was a significant decrease in isokinetic torque (8.45 Nm). There was a significant decrease in both mean isometric and isokinetic torque from day 1 to day 3 (12.67 and 13.59 Nm). Contrary to our hypothesis, no benefit from a practice session was found. Healthy, young adults are able to produce peak knee extensor torques on the first day of testing and do not demonstrate any benefit from additional testing. Thus, a practice day preceding isometric and isokinetic knee extensor strength testing may not be necessary when testing healthy, young participants, and may, in fact, negatively impact subsequent strength measurements

Cannabis and Cannabidiol Use in Active Individuals: A Survey of Timing and Reasons for Use

The use of cannabis for medicinal and recreational purposes is widespread across the globe. However, relatively little is known regarding the use of cannabis and its constituents among athletic populations. PURPOSE: The aim of this study was to examine timing of cannabis use relative to exercise, reasons for use, forms of consumption, and sources of information in active adults. METHODS: This cross-sectional survey was administered electronically beginning in September 2020. Participants were recruited through social media advertisements, email blasts, and word of mouth. Data were collected on health and exercise habits, use of cannabis/cannabidiol (CBD), reasons for use, form of consumption, and sources of information. RESULTS: 231 participants (82% ♂) completed the survey. Most participants exercised ≥3 d・wk-1 (84%) for ≥45 minutes a session (79.7%). Endurance sports were most common (47%), followed by functional/resistance training (11.3%) and sports participation (7.4%). 55% of the population self-described as “recreational exercisers” and 45% self-described as “competitive athletes”. 74% of participants reported using cannabis with THC, 15% reported using both cannabis with THC and CBD, and 11% only used CBD. 44% of participants used cannabis before and after exercise, with another 26% using cannabis after exercise only. 45% reported using cannabis before exercise for psychological reasons, while only 14% reported using for physiological reasons. Of those who only used cannabis after exercise, 36% reported using cannabis for psychological reasons, with 28% using it for rehabilitative purposes. Family/friends were the primary source of information (16%), followed by other media (14.5%; social media, podcasts, blogs, etc.), doctor or healthcare provider (14%), news media (13.3%), and sports coaches, teammates, and other athletes (12.8%). CONCLUSION: Results of the present study add to the meager data on cannabis use, exercise, and their interaction. It appears most active individuals believe that cannabis and CBD can improve the psychological aspects of exercise and assist with recovery from exercise. Adequately powered, well-controlled and conducted randomized trials are needed to further determine the influence of cannabis consumption on exercise performance and recovery

Protocol for quantifying the in vivo rate of protein degradation in mice using a pulse-chase technique

Summary: The ability to measure the in vivo rate of protein degradation is a major limitation in numerous fields of biology. Here, we present a protocol for quantifying this rate in mice using a pulse-chase technique that utilizes an azide-bearing non-canonical amino acid called azidohomoalanine (AHA). We describe steps for using chow containing AHA to pulse-label the animal’s proteome. We then detail the quantification of AHA-labeled proteins in whole-tissue lysates or histological sections using a copper-catalyzed azide-alkyne cycloaddition ‘click’ reaction.For complete details on the use and execution of this protocol, please refer to Steinert et al. (2023).1 : Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics

Efficacy and safety of two neutralising monoclonal antibody therapies, sotrovimab and BRII-196 plus BRII-198, for adults hospitalised with COVID-19 (TICO): a randomised controlled trial

We aimed to assess the efficacy and safety of two neutralising monoclonal antibody therapies (sotrovimab [Vir Biotechnology and GlaxoSmithKline] and BRII-196 plus BRII-198 [Brii Biosciences]) for adults admitted to hospital for COVID-19 (hereafter referred to as hospitalised) with COVID-19. In this multinational, double-blind, randomised, placebo-controlled, clinical trial (Therapeutics for Inpatients with COVID-19 [TICO]), adults (aged ≥18 years) hospitalised with COVID-19 at 43 hospitals in the USA, Denmark, Switzerland, and Poland were recruited. Patients were eligible if they had laboratory-confirmed SARS-CoV-2 infection and COVID-19 symptoms for up to 12 days. Using a web-based application, participants were randomly assigned (2:1:2:1), stratified by trial site pharmacy, to sotrovimab 500 mg, matching placebo for sotrovimab, BRII-196 1000 mg plus BRII-198 1000 mg, or matching placebo for BRII-196 plus BRII-198, in addition to standard of care. Each study product was administered as a single dose given intravenously over 60 min. The concurrent placebo groups were pooled for analyses. The primary outcome was time to sustained clinical recovery, defined as discharge from the hospital to home and remaining at home for 14 consecutive days, up to day 90 after randomisation. Interim futility analyses were based on two seven-category ordinal outcome scales on day 5 that measured pulmonary status and extrapulmonary complications of COVID-19. The safety outcome was a composite of death, serious adverse events, incident organ failure, and serious coinfection up to day 90 after randomisation. Efficacy and safety outcomes were assessed in the modified intention-to-treat population, defined as all patients randomly assigned to treatment who started the study infusion. This study is registered with ClinicalTrials.gov, NCT04501978. Between Dec 16, 2020, and March 1, 2021, 546 patients were enrolled and randomly assigned to sotrovimab (n=184), BRII-196 plus BRII-198 (n=183), or placebo (n=179), of whom 536 received part or all of their assigned study drug (sotrovimab n=182, BRII-196 plus BRII-198 n=176, or placebo n=178; median age of 60 years [IQR 50–72], 228 [43%] patients were female and 308 [57%] were male). At this point, enrolment was halted on the basis of the interim futility analysis. At day 5, neither the sotrovimab group nor the BRII-196 plus BRII-198 group had significantly higher odds of more favourable outcomes than the placebo group on either the pulmonary scale (adjusted odds ratio sotrovimab 1·07 [95% CI 0·74–1·56]; BRII-196 plus BRII-198 0·98 [95% CI 0·67–1·43]) or the pulmonary-plus complications scale (sotrovimab 1·08 [0·74–1·58]; BRII-196 plus BRII-198 1·00 [0·68–1·46]). By day 90, sustained clinical recovery was seen in 151 (85%) patients in the placebo group compared with 160 (88%) in the sotrovimab group (adjusted rate ratio 1·12 [95% CI 0·91–1·37]) and 155 (88%) in the BRII-196 plus BRII-198 group (1·08 [0·88–1·32]). The composite safety outcome up to day 90 was met by 48 (27%) patients in the placebo group, 42 (23%) in the sotrovimab group, and 45 (26%) in the BRII-196 plus BRII-198 group. 13 (7%) patients in the placebo group, 14 (8%) in the sotrovimab group, and 15 (9%) in the BRII-196 plus BRII-198 group died up to day 90. Neither sotrovimab nor BRII-196 plus BRII-198 showed efficacy for improving clinical outcomes among adults hospitalised with COVID-19. US National Institutes of Health and Operation Warp Spee