Introduction: Although many individuals are aware of the health benefits of regular exercise, few engage in it consistently. Stress, fatigue, and time pressures can deplete self-control resources, making it more difficult to prioritize exercise. When these resources are low, individuals may be more likely to choose activities based on automatic associations with pleasure and reflective evaluations of enjoyment rather than considering the long-term benefits. This tendency may lead individuals, particularly those who have negative perceptions of exercise, to remain sedentary. To address this challenge, we developed PlayFit (PF), a social physical play program designed to maximize exercise enjoyment. PF consists of modified sport-based games that are: (1) easier to play, (2) structured to encourage positive peer interactions, and (3) designed to support self-regulation of physical effort. Methods: Due to the COVID-19 pandemic, several significant modifications were made to the original registered trial design (see Methods section for details). Following these adjustments, the present study compared changes in exercise enjoyment and adherence over a 12-week period between two exercise programs matched for intensity, frequency, and duration: PF and a traditional group exercise program (Small Team Training; STT). Results: A total of 82 participants (38.3 ± 7.9 years of age; 76.8% female; BMI = 31.2 ± 8.1; VO2peak = 24.9 ± 7.9 ml/kg/min) were included in the final analysis. The PF group demonstrated a statistically significant increase in exercise enjoyment from baseline to week 12. There was no difference in the mean number of exercise sessions attended between the two groups, PF (14.0 ± 9.7 days) and STT (10.5 ± 9.6 days, p = 0.10). Conclusions: The observed increase in exercise enjoyment among PF participants suggests that enjoyment may be modifiable over time among adults with overweight or obesity and low cardiorespiratory fitness. These findings support the potential of programs like PlayFit to enhance exercise enjoyment. Future research, with adequate sample sizes and without pandemic-related constraints, is warranted to further explore the impact of intentionally designed enjoyment-focused interventions on long-term exercise adherence.

Background Hip joint osteoarthritis (OA) is a chronic condition that can significantly affect the energetic cost of walking. Exercise is a high-value method for the management and maintenance of function in people with hip joint OA. Walking economy is a measure of the energetic cost of steady-state walking and is associated with declines in physical activity. Previous research has highlighted the ability of exercise programs focusing on improving gait symmetry and reducing step-to-step variability to improve walking economy in older adults. It is unknown if walking economy can be influenced by neuromuscular exercise in those with hip joint OA. Therefore, this study aims to investigate the effects of a neuromuscular exercise program on walking economy in adults with hip joint OA. Methods Fifty individuals (25 per group) with hip joint OA will be recruited from the community. Following a baseline assessment, they will be randomly allocated to either 1) an exercise intervention or 2) a control group continuing usual care. The intervention group will undergo a 12-week neuromuscular exercise program focused on improving gait symmetry and reducing step-to-step variability in a group exercise setting. The primary outcome is walking economy at standard and preferred walking speeds. Secondary outcomes include spatiotemporal gait measures (step frequency, length, and width as well as stance and swing duration) and lower limb strength (handheld dynamometer, isometric mid-thigh pull, and wall sit test). Additional measures include self-reported pain, hip function, and physical activity, and body mass index (BMI). Discussion The findings from this study will assist practitioners in the prescription of exercises for individuals with hip joint OA. Specifically, we will determine whether a 12-week neuromuscular exercise program can improve walking economy and the likely mechanisms. Trial registration Australian New Zealand Clinical Trials Registry, registration number ACTRN12624000411549. Registered 4th April 2024.

IntroductionPast research highlighted that group fitness is an ideal format to meet exercise prescription guidelines. To add, a group enhances exertion, enjoyment, and satisfaction. In the last five years, streaming (live classes on screen with other participants visible) and on demand (pre-recorded classes on screen without other participants visible) formats have grown in popularity. Our goal is to compare the physiological intensity and psychological perceptions of live group, live streaming, and non-live on demand classes. We hypothesize that live classes will have the greatest cardiovascular intensity, enjoyment, and satisfaction followed by streaming and finally on demand.MethodsFifty-four adults between 18–63 years, who regularly participate in group fitness classes, recorded their heart rate with a chest transmitter during a mixed-martial arts cardiovascular class on consecutive weeks in random order. We calculated the mean, identified the max, and extracted the top 300 values (5 min) for comparison between conditions.ResultsFollowing each class, the participants completed an online survey to evaluate their rate of perceived exertion, enjoyment, and satisfaction. Confirming our hypothesis, mean class heart rate and mean heart rate for the five minutes at the highest intensity were 9% greater during the live group format compared to both live streaming and non-live on demand (all values, p < 0.01). However, there was no difference in any heart rate variables between the streaming and on demand formats. Also, rate of perceived exertion, enjoyment, and satisfaction were all significantly greater during the live session compared to the home collections (all values, p < 0.05).DiscussionStreaming and on demand group fitness formats are viable options for meeting exercise prescription guidelines. But physiological intensity and psychological perceptions were greater during the live class format.

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 < 0.001; ηp2 = 0.409) and echo intensity (p < 0.001; ηp2 = 0.558), and an increase in fat-free mass (p < 0.001; ηp2 = 0.367) and VO2peak (p = 0.001; ηp2 = 0.318). Muscle size was unaffected (p > 0.05), whereas peak torque was reduced similarly in both groups (p = 0.017; ηp2 = 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).

Determining lactate breakpoint and aerobic capacity using non-invasive field tests with minimal equipment is critical for athletes and coaches to assess training progress as well as to set accurate training intensity targets. PURPOSE: To calculate lactate breakpoint (LB) power output versus a predicted LB power and to compare measured oxygen consumption versus predicted maximum oxygen consumption. METHODS: 18 healthy athletes (3 women; age 18-71) completed two consecutive assessments. For the first test, we collected HR and venous blood lactate during 8, 4-minute stages of progressive power output. All blood lactate, HR and power values were then processed using a commercial analysis program to determine power at LB using the log-log exponential Dmax method (LLED). For the second test, we measured O2 consumption and CO2 production during warm-up, 1-minute incremental maximal ramp protocol, 6-minute recovery, and 12-minute HR constrained effort. Predicted VO2 max was calculated by averaging the 2.5 and 5.0 minute mean maximal power outputs achieved during the ramp protocol by 80 watts/liter of O2. Predicted LB power output was calculated via linear regression of power versus HR from the warm-up, constrained effort and ramp. We set 90.5% of the peak 1-minute HR as the intercept for the HR associated with predicted LB power. RESULTS: The predicted LB mean value of 231 watts was not statistically different from the mean LLED LB value of 233 watts (p = .65) with a high correlation between the two methods (R2 = .919). The predicted VO2 max value (3.93 L/min) was highly correlated with the measured VO2 max value (3.95 L/min, R2 = .923) and not statistically different (p = 0.72). CONCLUSION: Power output at lactate breakpoint and maximum oxygen consumption can be accurately predicted using a novel cycling assessment with heart rate and power output.

A well-established predictor of cycling performance is VO2 max, which is highly correlated with Maximal Aerobic Power (MAP). The best predictor of uphill cycling performance is watts per kilogram of body weight (WKG). Previous studies have shown power output is greater when cycling on an incline. However, there is minimal research investigating the performance impacts of time spent training on an incline. PURPOSE: To determine how training with dynamic incline (DI) impacts performance. Our hypothesis is that all participants who train twice a week with a structured plan will improve MAP but participants who train with DI will show greater WKG improvements during a simulated climb test. METHODS: Twenty-two active adults (5 women, mean age 45 + 8 years) were recruited based on access to a standardized at-home indoor trainer with DI. Participants were free to maintain their normal activity levels during the 6-week study. Weeks 1 and 6 consisted of a graded exercise test (GXT) at 0% incline and a 4.8 km simulated climb (SC) at an average 7% incline. Average intervention training time for weeks 2-5 was 1 hour 43 minutes. Participants were divided into TILT and FLAT groups. TILT completed all intervals at an 8% DI (47% of the total training time), while FLAT completed all training at a static incline of 0%. Power targets in both groups were based on GXT results. RESULTS: In agreement with our hypothesis, MAP was greater in both groups (TILT = 3.2%, FLAT = 2.3%) during the GXT after structured training (p < 0.05), but WKG was only greater (2.6%) in TILT during the SC (TILT, p < 0.05). CONCLUSION: Regular structured training can improve standard measures of cycling performance on a 0% incline regardless of training time at different inclines. However, spending significant time training with an incline >7% is necessary to see improvements in simulated climbing.

High variability in blood glucose is associated with earlier onset of disease in healthy adults without diabetes. More specifically, prospective studies demonstrate that higher glucose variability is associated with an increased risk of cardiovascular disease, Alzheimer's disease, frailty, cardiovascular death, and cancer death compared to lower glucose variability. Similarly, other prospective research illustrates that these fluctuations induce endothelial dysfunction and may accelerate the development of atherosclerosis. Unfortunately, there are limited data on glucose concentrations in individuals without diabetes. PURPOSE: To correlate lifestyle variables- exercise, nutrition, sleep, emotions- with glucose variability. METHODS: Thirty-five healthy, active adults (8 women, mean age 47 + 8 years) wore a continuous glucose monitor for two weeks, maintained their typical routines, and recorded the data. They also completed each planned exercise session with a heart rate chest transmitter. The study participants logged these training sessions (total time, intensity zones, perceived exertion) as well as daily meals (time of day, macronutrient grams), sleep (total time, subjective quality), and emotions (stress, motivation, fatigue). RESULTS: Daily glucose variability was significantly correlated (n = 532) with number of cardio sessions per day (ρ = -0.19, p < 0.0001), protein grams within the first meal of the day (ρ = -0.14, p < 0.0001), percent fat per day (ρ = -0.12, p < 0.0001), and subjective fatigue (ρ = 0.14, p < 0.0001). CONCLUSIONS: Our data demonstrate that there are multiple lifestyle factors that can minimize glucose variability and thereby potentially lower future disease risk. With respect to planned exercise, a greater number of independent cardio sessions is more impactful than a singular session for a longer duration. In terms of nutrition, greater protein grams at breakfast and a higher daily fat percentage lessen glucose variability. And finally, reducing fatigue through lifestyle choices may diminish detrimental fluctuations.

Dynamic (DYN) strength training is a critical component of performance; improving endurance and power. But skill level, movement restrictions, and supervision are all relevant considerations for safety before including dynamic strength training into a plan. Multiple studies show isometric strength training (ISO) to be an effective alternative. PURPOSE: To compare endurance (time to exhaustion, TTE) and power (maximal movement distance, MMD) after either ISO or DYN training. We hypothesize that ISO and DYN training will not differ in endurance (TTE) or power (MMD). METHODS: Eight adults (3 women, mean age 40 + 19 years) not actively strength training, completed upper and lower body assessments pre and post pilot intervention. We measured endurance with TTE for a push-up hold and single leg wall sit. Power was measured with MMD for a seated medicine ball push and vertical jump. After the initial assessment, participants were randomly assigned to the ISO or DYN group. The training plan consisted of 3 days/wk for 6 weeks, scaled for each individual using a linear progression based on their initial assessment results. The ISO group performed push up and single leg wall sit static holds while the DYN group performed push up and lunge repetitions using a metronome. Groups were matched for time under tension. RESULTS: In agreement with our hypothesis, endurance was significantly greater for both groups after training. Specifically, TTE was greater during upper (33%) and lower (34%) body post assessments (all values, p < 0.05). The ISO group showed greater gains in cumulative TTE (62% vs. 13%, p < 0.05) and max TTE (36% vs. 27%, p < 0.05) for the single leg wall sit. However, in contrast to our hypothesis, there was no significant difference in power for either the ISO or DYN group. CONCLUSION: ISO training is a practical alternative to DYN and can be used in place of, or in conjunction with, DYN training as a safe and effective way to improve endurance.

Prior to the coronavirus pandemic, the American College of Sports Medicine predicted that group fitness would be one of the top three fitness trends in 2020. Our past research highlights many of the reasons, such as greater levels of exertion, enjoyment, and satisfaction. A group enhances intensity in the form of higher heart rate during cardio classes as well as heavier weight selection during strength classes. Exercising together, with the ability to interact through physical contact, verbal encouragement, and facial expressions, leads to feelings of enjoyment and satisfaction. In the last five years, virtual (live classes on screen with other participants visible) and on demand (pre-recorded classes on screen without other participants visible) options have grown in popularity. Over 85% of gym members complete regular exercise sessions at home and these numbers are only increasing with the repercussions of the global pandemic. PURPOSE: Our goal is to compare the physiological intensity and psychological perceptions of live, virtual, and on demand classes. We hypothesize that live classes will have the greatest cardiovascular intensity, enjoyment, and satisfaction followed by virtual and finally on demand. METHODS: To date, 37 adults between 18-63 years, who regularly participate in Les Mills group fitness classes, recorded their heart rate during all three formats (live, virtual, on demand) during BODYCOMBAT on consecutive weeks in random order. Following each class, they completed an online survey to evaluate their rate of perceived exertion, enjoyment, and satisfaction. RESULTS: Confirming our hypothesis, mean class heart rate and mean heart rate for the five minutes at the highest intensity were 9% greater during the live format compared to both virtual and on demand (all values, p < 0.01). However, there was no difference in any heart rate variables between the virtual and on demand formats. To add, rate of perceived exertion, enjoyment, and satisfaction were all significantly greater during the live session compared to the home collections (all values, p < 0.05). CONCLUSIONS: Virtual and on demand group fitness formats are viable options for maintaining regular physical activity routines. But live classes are ideal to maximize both physiological intensity and psychological perceptions.

The American College of Sports Medicine recognizes the benefits of high intensity interval training (HIIT) for the improvement of health, fitness, and performance. They also support the recent surge in research focused on HIIT to refine our understanding of the relationship between frequency, duration, and intensity. The current literature provides valuable information towards this goal correlated with demographics (age, sex) utilizing various singular intensity assessments (functional threshold, maximal aerobic, anaerobic). However, it is optimal to utilize an integrated protocol with diverse participants to provide more concrete guidelines specific to various training targets. PURPOSE: To evaluate the connection between demographics and intensity to provide accurate training parameters for maximal gains in health, fitness, and performance. We hypothesize that the correlation between peak cycling power over varying durations is significantly different depending on sex and age. METHODS: Seven thousand, one hundred and sixty-two individuals (3581 men, 3581 women matched for age) completed a single session, multidimensional indoor cycling test to assess neuromuscular power (NMP; 2, 7-second sprints), maximal aerobic power (MAP; 5-minute maximal effort), functional threshold power (FTP; 20-minute maximal effort) and anaerobic power (AP; 1-minute maximal effort). RESULTS: In agreement with our hypothesis, there was a statistically significant effect for sex (male, female; p-value < 0.0001) and age category (20-29, 30-39, 40-49, 50-59, 60-69 years; p < 0.0001) as well as a significant interaction between sex and age category (p < 0.0001) for each of the four power intensities (watts/kg). More specifically, power significantly decreased with age and the decline was greatest at the highest intensity (NMP) for both sexes. Also, the decrease in power with advancing age was significantly less in women compared to men apart from NMP. CONCLUSIONS: Our data demonstrates that all peak power durations progressively decline with age and women maintain their aerobic power more than men. Due to these significant interactions, high intensity exercise targets can only be prescribed accurately with multidimensional assessment tests.

The purpose of this study was to investigate the feasibility, acceptability, and short-term adherence to an adult outdoor group sport play program designed to maximize enjoyment that was modified to incorporate COVID-19 risk mitigation strategies. We enrolled 17 healthy, but sedentary, central Pennsylvania adults (meanage = 31.6 ± 7.3) without obesity via mail advertisements to participate in four, 60-minute sessions of instructor-led modified sport games (e.g., handball, Ultimate Frisbee, soccer) over a two-week period in October 2020. Durign recrutiment and the study period, there were approximately 1000–2000 new cases of COVID-19 daily in central Pennsylvania . The overall adherence rate to the sessions was 91%, and no participants reported new or existing COVID-19 symptoms or diagnoses during the two-week study period or 10-days following the final session. Despite enforcing mandatory COVID-19 safety measures (e.g., universal masking, social distancing), the participants reported enjoying the program and feeling socially connected with one another, while perceiving the program to be safe. Additionally, all participants expressed a desire to participate again, if the program were offered in the future. These results suggest that an outdoor group sport play program for adults can be feasible, acceptable, and well-adhered to despite enforcing mandatory COVID-19 safety precautions. Physical activity programs similar to the one presented here may provide an easily-adaptable approach to outdoor physical activity during the current and potential future pandemics that have viral transmission characteristics similar to COVID-19.

Despite the myriad benefits associated with regular physical activity (PA), few American adults accrue sufficient weekly PA. Although “lack of time” is often cited as a correlate of physical inactivity, a growing body of evidence suggests that, perhaps more importantly, people allocate their leisure-time to activities they find more enjoyable than PA. These findings underscore the need to devise physical activities that will be chosen over other enjoyable, but less healthy, behavioral alternatives. As a first step in this direction, we designed a group social PA play program for adults, known as PlayFit. The overarching philosophy of PlayFit is that fun and enjoyment are among the most important influences on PA adherence. In PlayFit, traditional sport games are modified to fulfill basic psychological needs, in a non-competitive, and non-contact environment. We will randomize 280 sedentary adults 18–50 years of age to 12-months of PlayFit or traditional group exercise, matching the groups on intensity, frequency, and duration. The primary outcomes include cardiorespiratory fitness (VO2peak), group adherence, and group enjoyment. We hypothesize that, at 6 months, cardiorespiratory fitness will have increased to the same extent in both groups, but at 12 months, only those randomized to PlayFit will have maintained their fitness through better adherence than Group Exercise – and this outcome will be mediated by enjoyment of the assigned group. Findings from this study could provide evidence that a focus on providing fun and enjoyable PA experiences for adults may be a viable route toward improving PA adherence. A simple, inexpensive PA intervention, such as PlayFit, may represent one such approach to do so.

Physical and mental health is a prevailing research topic as adults balance the demands of daily life. One strategy to maintain wellbeing is to adhere to a physical activity routine. Countless studies have demonstrated that regular exercise increases fitness and decreases depression. Therefore, recent investigations focus on protocols to easily measure the effectiveness of specific programs to maximize benefits. Heart rate variability (HRV) is an example of a noninvasive variable that provides insight about cardiovascular health and recovery. Stretching and meditation are two practices that past research has demonstrated increase HRV. PURPOSE: To evaluate if a fusion of stretching and meditation improves heart rate variability, positive feelings, and quality sleep in active adults. Our hypothesis is that performing a sequence of stretches (20-30 minutes) with subsequent meditation (10 minutes) three nights per week will enhance recovery (higher HRV) in addition to induce positive feelings and quality sleep. METHODS: Sixty-six adults between 24-67 years who regularly exercised at least five hours per week, without stretching or meditation, collected their morning heart rate and exercise heart rate with a chest transmitter for two weeks. Next, we assigned (age and activity matched) half the participants to an experimental stretching and meditation protocol three nights per week. Both groups continued the heart rate collection for another two weeks. Each participant also completed a weekly survey with questions addressing their satisfaction with life, physical as well as mental feelings, and quality of sleep. RESULTS: In the experimental group, heart rate variability, positive feelings (confidence, motivation), and quality sleep were significantly greater during the second two weeks while resting heart rate and negative feelings (sadness, anxiety) were significantly less (all comparisons p < 0.02). To contrast, in the control group, there were no significant differences between the measurement weeks. CONCLUSIONS: Our data demonstrate that 30-40 minutes of stretching and meditation three nights per week can be an effective routine to enhance both physical and mental health in active adults.

The growing prevalence and popularity of interval training necessitate additional guidelines in regard to maximal levels of time and intensity. Purpose: To correlate salivary hormones and time in varying heart-rate (HR) zones. The hypothesis was that chronic exercise durations >9% of total exercise time in the >90% maximum HR zone would lead to decreased variation in salivary cortisol concentration after exercise in a 2-bout high-intensity protocol compared with less or more time in this zone. Methods: A total of 35 healthy adults who regularly exercised for an average of 8 hours per week recorded their HR during every training session for 3 weeks. Later, they completed an experimental day composed of two 30-minute high-intensity interval sessions separated by 4 hours of nonactive recovery. The authors collected saliva samples before, immediately following, and 30 minutes after each exercise session to assess changes in cortisol concentrations. Results: There was a correlation between weekly time training at an intensity >90% maximum HR and the variables associated with overtraining. Salivary cortisol concentration fluctuated less in the participants who exercised in this extreme zone for >40 minutes per week (P < .001). Conclusion: Based on the current study data, for individuals who regularly exercise, 4% to 9% total training time above 90% maximum HR is the ideal duration to maximize fitness and minimize symptoms related to overreaching.

BACKGROUND:Over 60 million Americans participate in running as a form of exercise or sport annually, making it the most popular form of physical activity in the country. Although there are numerous health benefits from a regular running routine, it is also an activity associated with a high risk of injury. Multiple factors, such as core muscle weakness and stride asymmetry, contribute to running injuries and loss of performance. The aim of this study was to assess how an integrated, functional core training intervention affects the components of performance (metabolic economy and speed) as well as a risk factor associated with injury (range of motion joint asymmetry). We hypothesized that economy, 5-km speed, and range of motion symmetry would increase in runners who added a 6-week integrated core-training intervention to their routine compared to a control group who simply maintained their current running routine.METHODS:Twelve, healthy adult runners participated in the study and six of these participants completed the exercise intervention. Heart rate data were collected to estimate metabolic economy while kinematic data were collected to calculate joint range of motion asymmetry.RESULTS:Our data demonstrated that running asymmetry decreased by a statistically significant 60% at the ankle in the sagittal plane while economy was 3% greater on both level and incline surfaces.CONCLUSIONS:In summary, runners who completed the 6-week integrated, functional training intervention improved economy, 5-km speed, and range of motion symmetry in comparison to the runners who simply maintained their current training routine.

Group-based settings are valuable for promoting physical activity when individuals perceive high groupness, or when they feel like they are exercising in a true group (Spink, Wilson. & Priebe, 2010). Guided by basic needs theory (Deci & Ryan, 2(XX)). we tested a mechanistic model that examined the extent that groupness perceptions within fitness classes predicted satisfaction of basic needs (i.e., competence, relatedness, and autonomy) and, in turn. basic needs predicted general satisfaction as well as weekly group fitness bouts. Exercisers in fitness facilities in the United States and New Zealand (N = 293, M-age = 35.93, SD = 11.44, 78% female, 22% male) completed a survey directly following a class entailing groupness subscales of Entitativity (e.g., perceiving the collective as a group) and Group Structure (e.g., reporting group norms), followed by an online survey 3 weeks afterward. Multiple mediation models revealed an indirect effect of groupness subscales through basic need satisfaction, on both general satisfaction and weekly fitness bouts. Autonomy and relatedness were the strongest mediators when predicting general satisfaction, whereas relatedness was the strongest mediator when predicting weekly fitness bouts. These findings support the use of basic needs theory for understanding how exercisers are influenced by their groups. Practically, groupness-enhancing strategies have the potential to impact belongingness along with competence and autonomy perceptions as critical evaluations for promoting health behavior.

Objective: How can we distinguish between a collection of individuals exercising alongside one another from group that is exercising 'together'? This question is central to research on the extent that individuals perceive their fitness settings to entail core features of groups. To advance understanding of the nature of groupness and its implications in exercise, the current study (a) evaluated a brief measure of groupness and (b) examined the extent that groupness predicted perceptions of exertion and affect. Design: Participants included 633 exercisers (M-age = 33.92, SD = 11.05, 74% female) who completed surveys after group fitness classes (k = 34). Main outcome measures: Groupness, affect, exertion, and group cohesion. Results: Exploratory structural equation modelling provided support for a two-factor solution reflecting entitativity and group structure as subdimensions of groupness. The groupness factors were differentially associated with theoretically relevant aspects of classes (e.g. synchronised movement), the individual (e.g. number of members interacted with), as well as group cohesion. Groupness also predicted perceived exertion and affect. Conclusion: Our research provides support for a brief measure of groupness, advances theory related to how individuals perceive exercise groups, and provides evidence regarding how broader experiences during exercise may relate to exercisers' perceptions of groupness.

Group contexts such as fitness classes are popular forms of physical activity, and studying them can uncover new ways to promote exercise adherence. Focusing on the potential for group fitness experiences to vary from class-to-class, we examined how exercisers' dynamic perceptions of groupness relate to recalled perceptions of exercise enjoyment, affective valence, and exertion. These outcome variables are in focus because they are theoretically construed to be determinants of physical activity. Using an intensive sampling methodology across a two-week period, 97 adult exercisers (M age = 42.35 years) completed surveys following each fitness class attended (695 unique responses). Using multilevel confirmatory factor analysis, we confirmed a theorized two-factor structure of groupness at both the within-and between-person levels. Multilevel modeling revealed that class-to-class fluctuations in exercisers' perceptions of groupness explained a considerable portion of variance in recalled perceptions of exertion, enjoyment, and affective valence. Specifically, during classes in which exercisers' perceptions of groupness were relatively higher, exercisers reported more recalled enjoyment, affective valence, and exertion. Focusing on how variability in groupness perceptions may influence exercise adherence, these findings demonstrate the value in fitness classes feeling like authentic groups. In studying the dynamic aspects of group evaluations, the current study makes novel advancements to group theories applied to exercise settings. Perhaps most notably, individuals' variations in their cognitive evaluations of fitness groups were closely linked to their affective responses to exercise.