Abstract
PurposeSarcopenia can begin from the 4–5th decade of life and is exacerbated by obesity and inactivity. A combination of resistance exercise (RE) and endurance exercise is recommended to combat rising obesity and inactivity levels. However, work continues to elucidate whether interference in adaptive outcomes occur when RE and endurance exercise are performed concurrently. This study examined whether a single bout of concurrent RE and high-intensity interval training (HIIT) alters the satellite cell response following exercise compared to RE alone.MethodsEight sedentary, overweight/obese, middle-aged individuals performed RE only (8 × 8 leg extensions at 70% 1RM), or RE + HIIT (10 × 1 min at 90% HRmax on a cycle ergometer). Muscle biopsies were collected from the vastus lateralis before and 96 h after the RE component to determine muscle fiber type-specific total (Pax7+ cells) and active (MyoD+ cells) satellite cell number using immunofluorescence microscopy.ResultsType-I-specific Pax7+ (P = 0.001) cell number increased after both exercise trials. Type-I-specific MyoD+ (P = 0.001) cell number increased after RE only. However, an elevated baseline value in RE + HIIT compared to RE (P = 0.046) was observed, with no differences between exercise trials at 96 h (P = 0.21). Type-II-specific Pax7+ and MyoD+ cell number remained unchanged after both exercise trials (all P ≥ 0.13).ConclusionCombining a HIIT session after a single bout of RE does not interfere with the increase in type-I-specific total, and possibly active, satellite cell number, compared to RE only. Concurrent RE + HIIT may offer a time-efficient way to maximise the physiological benefits from a single bout of exercise in sedentary, overweight/obese, middle-aged individuals.
Highlights
Ageing often results in the degenerative loss of significant muscle mass and strength, known as sarcopenia (Bijlsma et al 2013), a process starting as early as the 4th or 5th decade (Marcell 2003; Jackson et al 2012)
We have recently shown that using an acute bout of high-intensity interval training (HIIT) in combination with resistance exercise (RE), as an alternative to moderate-intensity endurance exercise with RE, does not impede acute (< 6 h) gene expression and protein signalling markers of muscle growth compared to a single bout of RE alone in young, healthy individuals (Pugh et al 2015)
The data from the current study suggest that concurrent RE + HIIT does not impair the elevation in satellite cell content, in type I fibers, 96 h after a single bout of RE, which is in contrast to a similar study that employed moderate-intensity continuous endurance exercise instead of HIIT (Babcock et al 2012)
Summary
Ageing often results in the degenerative loss of significant muscle mass and strength, known as sarcopenia (Bijlsma et al 2013), a process starting as early as the 4th or 5th decade (Marcell 2003; Jackson et al 2012). Exercise can lessen the effect of sarcopenia, 45% of women and 33% of men do not meet the current physical activity guidelines (Health and Social Care Information Centre 2013). Sarcopenia is further accelerated in the presence of obesity and can result in physical disability and a lower quality of life (Dominguez and Barbagallo 2007; Stenholm et al 2008) and in England, 58% of women and 65% of men are classified as overweight or obese (Health and Social Care Information Centre 2016). Current exercise guidelines recommend that middle-aged individuals (~ 40 to 65 years) should engage in a combination of endurance and resistance exercise (RE), improve cardio-metabolic health and quality of life (Chief Medical Office 2011; Garber et al 2011). It is often recommended that individuals should complete five 30 min sessions of moderate-intensity endurance exercise and two sessions of RE per week, requiring up to 7 days of exercise engagement per week, which may provide a significant barrier to some
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