The results suggest that the exercise intervention group experienced increased happiness, resilience, and well-being, accompanied by lower perceived stress. The intervention group had higher average scores on FL1, FL2, FL3, FL4, FL6, and hand grip, while it had lower scores on FL5. It should be noted that the post-hoc tests (interaction) did not show statistical significance in hand grip, FL4, FL5, and SWL. However, the overall interaction effects in the linear mixed models were significant. This finding suggests differences in scores among groups over time in these variables. However, perhaps because of lower power, the differences were not detected in post-hoc tests after adjusting p-values.
The key findings of this 16-week functional fitness exercise intervention, delivered thrice weekly, reveal that the exercise program successfully induced both physical and psychological changes in the exercise intervention group compared to the control group. Therefore, this specific exercise intervention benefits older adults above 60, and most benefits occur already after eight weeks or 24 exercise sessions, as revealed by objective (physical measurements) and subjective (questionnaire data) measurements. Such changes benefit older adults regarding physical functioning and mental health. Larger scale studies using the here-adopted program could strengthen these findings and might have applied value in enhancing the quality of life of older adults.
Psychological Measures
Subjective happiness rose after eight weeks in the exercise group, consistent with short-term intervention studies reported in the literature (Greenawalt et al. 2018; Khazaee-Pool et al. 2014; Tse et al. 2014; Turner et al. 2017). As expected, subjective happiness also remained higher in the intervention group after 16 weeks, matching the results of earlier, more extended exercise intervention studies (McAuley et al. 2000; Moeini et al. 2020; Orsega-Smith et al. 2018). One of these studies (McAuley et al. 2000) found no difference between different exercise forms in enhancing happiness after a more extended intervention program. Thus, it appears that several forms of physical activity impact older adults' subjective happiness.
We found no changes in SWL over time in the intervention group. However, the control group seemed to decline in this measure during the study period. We have no explanation for this finding, but we speculate that a dissatisfaction that they could not participate in the exercise program at the same time as the intervention group could have been conveyed in their responses. Consistent with our findings, Ornes et al. (2005) examined three generations of women in a six-month exercise intervention study and found no changes in SWL. In this context, Syue et al. (2022) found that the effect on functional fitness training was only observed at moderate to high levels of physical activity. In contrast, Blace (2012) suggested a mediating role for functional fitness in the relationship between physical activity and SWL, supported by some earlier studies (Kahazee-Pool et al. 2014; Tse et al. 2014). Our contradictory findings suggest that the connection between physical activity and SWL in older adults is mediated by multiple factors that need further elucidation.
Our results on resilience are consistent with the recent literature review of Toth et al. (2023). The intervention and control groups did not differ at baseline or after eight weeks. However, after the intervention, the resilience scores of the exercise group were significantly higher. The type and duration of exercise intervention could be instrumental in fostering resilience in older adults (Toth et al. 2023). The current results suggest that the functional fitness training adopted here (Appendix) efficiently improves psychological resilience.
The 16-week intervention significantly reduced perceived stress levels. An improvement occurred after eight weeks. These results match the results of Papageorgiou et al. (2016), who found positive effects of multimodal stress management on older women's mental and physical health. The results also support Hewett et al.’s (2018) research, showing that a 16-week Bikram yoga positively affected perceived stress among adults at both eight and 16-week assessment points. Time-based, these findings are consistent with our results. Therefore, the exercise program used in this study has relatively fast benefits on the participants' perceived stress.
We found the most significant positive change in mental well-being. There was a significant difference between the control and exercise groups halfway through the intervention and after 16 weeks. These findings agree in part with a 12-month longitudinal study of the effects of a structured group exercise program for older adults in which the total daily physical activity energy expenditure and the amount of time spent in at least moderate intensity activity were weakly associated with the subjective well-being (Fox et al. 2007). They contrast with an early study by Perrig-Chiello et al. (1998), showing no difference in mental well-being between the intervention and control groups after eight weeks of resistance training. Similarly, Stoll and Alfermann (2002) trained older people in endurance, strength, coordination, and flexibility and found no change in mental well-being after 14 weeks. Thus, while different physical activity intervention studies report heterogeneous findings in well-being, the current exercise program seems to affect this measure favorably.
Functional Fitness Measures
A 16-week specific exercise program successfully improved the functional fitness of older adults. Since we could not find a longitudinal study in the literature to compare our results, we focused on studies that measured physical fitness in older adults using the Fullerton test. We found significant differences between the treatment and control groups in almost all variables at week eight and post-intervention. The lower limb (FL1) and upper limb strength (FL2) of the intervention group showed an almost equal rate of improvement after 16 weeks (Table 3.) The results measured after the intervention are consistent with the findings in the active older adults (Umiastowska et al. 2020). High-intensity lower limb strength training can improve strength better than lower-intensity strength training, although it may not be necessary for functional improvement.
Studies in which groups performed the same training volume resulted in similar gains in leg strength, regardless of training intensity (Raymond et al. 2013). Penn et al. (2019) conducted an eight-week Tai Chi intervention in older people, significantly increasing lower limb strength and balance. Targeted upper limb strength training also resulted in significant changes in functional upper limb strength, shoulder joint range of motion, and grip strength in older adults after eight weeks (Kim et al. 2022). The intervention group showed a 23% improvement in upper limb flexibility (FL3) after 16 weeks compared to baseline measurements (Table 3.) Ihász et al. (2020) found similar results in women aged 60–70 years.
Lower limb flexibility (FL4) improved by approximately 65% compared to baseline measurements. The age group classification by Rikli and Jones (1999) showed that the average for the intervention group is like the average standard value for the 70–74 age group. There is limited literature on the role of flexibility in maintaining or improving functional ability. Findings suggested that flexibility-specific interventions may affect the range of motion outcomes. However, there is conflicting information regarding the relationship between flexibility interventions and functional outcomes or daily functioning (Stathokostas et al. 2012). The intervention participants' average mobility and balance test (FL5) scores after 16 weeks were in line with the standard scores defined by Rikli and Jones (1999) for the 80–85 age group. Physical training (e.g., Tai Chi and strength training) has been shown to improve balance and prevent falls. For more than eight weeks, balance training for 90–120 minutes per week significantly reduced falls and improved balance control (Chen et al. 2021). In our study, the most significant proportion of changes was in lower limb flexibility and complex coordination, which is assumed to have implications for fall prevention. The results showed the least increase in endurance, possibly due to lower cardiovascular adaptation.
Skill | Baseline | After 8 weeks | After 16 weeks | Change1 (%) | Change2 (%) |
FL1 | 13.1 | 14.1 | 15.2 | 7 | 14 |
FL2 | 16.9 | 18.4 | 19.8 | 8 | 15 |
FL3 | -16.2 | -13.7 | -12.5 | 15 | 23 |
FL4 | -3.1 | -1.5 | -1.1 | 52 | 65 |
FL5 | 12.1 | 10.2 | 9.3 | 9 | 23 |
FL6 | 79.8 | 84.0 | 87.8 | 5 | 9 |
Dynamo ** | 21.3 | 22.6 | 24.0 | 6 | 11 |
Note. FL1 = lower limb strength (number of repetitions in 30 sec); FL2 = upper limb strength (number of repetitions in 30 sec); FL3 = upper body flexibility (+/- cm); FL4 = lower body flexibility (+/- cm); FL5 = agility and balance (seconds); FL6 = step in place (number of repetitions in 120 sec), Change1 = 8th week compared to baseline, Change2 = after 16 weeks compared to baseline
Table 3 Fullerton skills and changes at 8th week and after 16 weeks