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The physiological control of appetite regulation involves circulating hormones with orexigenic (appetite-stimulating) and anorexigenic (appetite-inhibiting) properties that induce alterations in energy intake via perceptions of hunger and satiety. As the effectiveness of exercise to induce weight loss is a controversial topic, there is considerable interest in the effect of exercise on the appetite-regulating hormones such as acylated ghrelin, peptide YY (PYY), glucagon-like peptide-1 (GLP-1), and pancreatic polypeptide (PP). Research to date suggests short-term appetite regulation following a single exercise session is likely affected by decreases in acylated ghrelin and increases in PYY, GLP-1, and PP. Further, this exercise-induced response may be intensity-dependent. In an effort to guide future research, it is important to consider how exercise alters the circulating concentrations of these appetite-regulating hormones. Potential mechanisms include blood redistribution, sympathetic nervous system activity, gastrointestinal motility, cytokine release, free fatty acid concentrations, lactate production, and changes in plasma glucose and insulin concentrations. This review of relevant research suggests blood redistribution during exercise may be important for suppressing ghrelin, while other mechanisms involving cytokine release, changes in plasma glucose and insulin concentrations, SNS activity, and muscle metabolism likely mediate changes in the anorexigenic signals PYY and GLP-1. Overall, changes in appetite-regulating hormones following acute exercise appear to be intensity-dependent, with increasing intensity leading to a greater suppression of orexigenic signals and greater stimulation of anorexigenic signals. However, there is less research on how exercise-induced responses in appetite-regulating hormones differ between sexes or different age groups. A better understanding of how exercise intensity and workload affect appetite across the sexes and life stages will be a powerful tool in developing more successful strategies for managing weight.

Sprint interval training (SIT) can elicit improvements in aerobic and anaerobic capacity. While variations in SIT protocols have been investigated, the influence of social processes cannot be overlooked. As research supports the use of groups to influence individual cognitions and behaviours, the current project assessed the effectiveness of a group-based intervention with participants conducting SIT. Specifically, 53 amateur athletes (age, 21.9 ± 2.9 years; 53% females) took part in a 4-week training program (3 sessions per week, 30-s “all-out” efforts with 4 min active recovery, repeated 4–6 times per session), and were assigned to “true group”, aggregate, or individual conditions. Results indicated no significant differences between groups for the physiological measures. With regards to training improvements from baseline for all participants— regardless of condition — significant main effects for time were identified for maximal oxygen uptake (2.5–2.8 mL·kg−1·min−1, p < 0.001, η2 = 0.03), time-trial performance (14–32 s, p < 0.001, η2 = 0.37), and anaerobic power (1.1–1.7 k·h−1, p < 0.001, η2 = 0.66). With regards to the psychological measures, significant main effects between groups were found for motivation (p = 0.033, η2 = 0.13), task self-efficacy (p = 0.018, η2 = 0.15), and scheduling self-efficacy (p = 0.003, η2 = 0.22). The true group experienced greater improvements in motivation than the individual condition, but the aggregate and individual conditions demonstrated greater increases in task and scheduling self-efficacy. Though the SIT paradigm employed induced training improvements similar to previous work, the group intervention was not able to further these improvements.

The purpose of this study was to determine the effectiveness of a 4-week running sprint interval training protocol to improve both aerobic and anaerobic fitness in middle-aged adults (40-50 years) as well as compare the adaptations to younger adults (20-30 years). Twenty-eight inactive participants - 14 young 20-30-year-olds (n = 7 males) and 14 middle-aged 40-50-year-olds (n = 5 males) - completed 4 weeks of running sprint interval training (4 to 6, 30-s "all-out" sprints on a curved, self-propelled treadmill separated by 4 min active recovery performed 3 times per week). Before and after training, all participants were assessed for maximal oxygen consumption (VO2max), 2000 m time trial performance, and anaerobic performance on a single 30-s sprint. There were no interactions between group and time for any tested variable, although training improved relative VO2max (young = 3.9, middle-aged = 5.2%; P 0.04), time trial performance (young = 5.9, middle-aged = 8.2%; P 0.001), peak sprint speed (young = 9.3, middle-aged = 2.2%; P 0.001), and average sprint speed (young = 6.8, middle-aged = 11.6%; P 0.001) in both young and middle-aged groups from pre- to post-training on the 30-s sprint test. The current study demonstrates that a 4-week running sprint interval training programme is equally effective at improving aerobic and anaerobic fitness in younger and middle-aged adults.

This study aimed to determine whether a time-effective whole-body aerobic resistance training circuit using only body weight exercises is as effective in improving aerobic and anaerobic fitness, as well as muscular strength and endurance as a traditional concurrent style training combining resistance and endurance training. Thirty-four sedentary females (20.9 ± 3.2 years; 167.6 ± 6.4 cm; 65.0 ± 15.2 kg) were assigned to either: (a) a combined resistance and aerobic exercise group (COMBINED; n = 17) or (b) a circuit-based whole-body aerobic resistance training circuit group (CIRCUIT; n = 17). Training was 3 days per week for 5 weeks. Pre- and post-training measures included a (Equation is included in full-text article.)test, anaerobic Wingate cycling test, and muscular strength and endurance tests. After training, (Equation is included in full-text article.)improved with CIRCUIT by 11% (p = 0.015), with no change for COMBINED (p = 0.375). Both relative peak power output and relative average power output improved with CIRCUIT by 5% (p = 0.027) and 3.2% (p = 0.006), respectively, and with COMBINED by 5.3% (p = 0.025) and 5.1% (p = 0.003). Chest and hamstrings 1 repetition maximum (1RM) improved with CIRCUIT by 20.6% (p = 0.011) and 8.3% (p = 0.022) and with COMBINED by 35.6% (p < 0.001) and 10.2% (p = 0.004), respectively. Only the COMBINED group improved back (11.7%; p = 0.017) and quadriceps (9.6%; p = 0.006) 1RM. The COMBINED group performed more repetitions at 60% of their pretraining 1RM for back (10.0%; p = 0.006) and hamstring (23.3%; p = 0.056) vs. CIRCUIT. Our results suggest that a circuit-based whole-body aerobic resistance training program can elicit a greater cardiorespiratory response and similar muscular strength gains with less time commitment compared with a traditional resistance training program combined with aerobic exercise.