Resistance training protects against muscle pain through activation of androgen receptors in male and female mice.

ABSTRACT: Resistance training-based exercise is commonly prescribed in the clinic for the treatment of chronic pain. Mechanisms of aerobic exercise for analgesia are frequently studied, while little is known regarding resistance training mechanisms. We developed a resistance training model in mice and hypothesized resistance training would protect against development of muscle pain, mediated through the activation of androgen receptors. Activity-induced muscle hyperalgesia was produced by 2 injections of pH 5.0 stimuli with fatiguing muscle contractions. Resistance training was performed by having mice climb a ladder with attached weights, 3 times per week. Resistance training acutely increased blood lactate and prolonged training increased strength measured via forepaw grip strength and 1 repetition maximum, validating the exercise program as a resistance training model. Eight weeks of resistance training prior to induction of the pain model blocked the development of muscle hyperalgesia in both sexes. Resistance training initiated after induction of the pain model reversed muscle hyperalgesia in male mice only. A single resistance training bout acutely increased testosterone in male but not female mice. Administration of the androgen receptor antagonist flutamide (200 mg pellets) throughout the 8-week training program blocked the exercise-induced protection against muscle pain in both sexes. However, single administration of flutamide (1, 3, 10 mg/kg) in resistance-trained animals had no effect on existing exercise-induced protection against muscle pain. Therefore, resistance training acutely increases lactate and testosterone and strength overtime. Eight weeks of resistance training prevents the development of hyperalgesia through the activation of androgen receptors in an animal model of muscle pain.

#NicotineAddictionCheck: Puff Bar Culture, Addiction Apathy, and Promotion of E-Cigarettes on TikTok.

This study aimed to classify and delineate types of user-generated content about the disposable e-cigarette Puff Bar shared on the popular video-based social media platform TikTok. We qualitatively analyzed 148 popular TikTok videos collected in July 2020. During an iterative process of data reduction and thematic analysis, we categorized videos by overarching genres and identified emergent themes. Young adults were engaged at all stages of the research process. Together, videos were viewed over 137 million times on TikTok. Seven genres of Puff Bar content emerged: skits and stories, shared vaper experiences, videos to show off, product reviews, product unboxing, promotion of Puff Bar, and crafts. Videos depicted Puff Bar users' apathy about addiction and a lack of concern of the health effects of e-cigarette use. Additionally, Puff Bar promotion content from underground retailers was extensive and some targeted underage persons. Qualitative analysis of social media content can richly describe emerging online culture and illuminate the motivations of adolescent and young adult e-cigarette use. Social media can facilitate new product adoption; comprehensive e-cigarette regulation and enforcement can counteract these effects by closing loopholes through which new products emerge.