Introduction
Aging is a global concern that is associated with a decline in organ function and makes a person vulnerable to diseases. Falling is one of the causes of injuries in older adults [1]. Stair climbing is a problematic activity and one of the most common causes of falls in older adults [2, 3]. The elderly are three times more likely to fall when walking up the stairs than when walking on the ground [4]. Balance disorders make stair climbing difficult for the elderly [5]. Controlling balance while climbing stairs is more difficult than that when walking [6]. Most of studies have focused on improving the balance of the elderly while walking, and less attention has been paid to their stair-climbing performance. The mechanisms of balance improvement are different. Combined and multi-component training programs may cause better results in balance improvement [7]. The present study aims to investigate the effect of combined exercises on the stair negotiation performance of older men.

Methods
This is a randomized controlled clinical trial with a pre-test/post-test design. Thirty older men were selected and randomly allocated to two parallel groups of intervention and control. The intervention group performed 12 weeks of combined exercises, while the control group continued their usual activities during this period. Inclusion criteria were age at least 60 years, functional independence, obtaining the required scores in the general health questionnaire-28, mini-mental state examination, and physical activity readiness questionnaire; no any medical and ethical restrictions, ability to complete tests and exercises, and no participation in other regular exercise programs. Exclusion criteria included an unwillingness to participate in tests and absence from exercise sessions. The participants performed the stair negotiation tests and their kinetic and kinematic data were recorded using the Kistler force plate and the Qualisys motion capture system. The balance was measured with the center of pressure (COP) parameters [1]. The stair ascending and descending time was calculated with kinematic data. Stair negotiation performance was evaluated with the timed up and down stairs (TUDS) test [8], and the self-efficacy was evaluated with the stair self-efficacy (SSE) scale [9]. The exercise protocol consisted of warm-up (10 minutes), resistance training (20 minutes), balance, hopping, and jump training (40 minutes), and cooling down (5 minutes) for 12 weeks. The overload principle was observed with a gradual increase in the duration, number, and load amount. Statistical analysis was carried out using mixed ANOVA. Pairwise comparison was done with the Bonferroni test, and the effect size (partial eta squared) was calculated [10]. The significance level was set at 0.05. 

Results
Descriptive information and the results of mixed ANOVA for the stair negotiation variable are reported in Table 1.


Interaction effects of the COP parameters, including range and velocity in anteroposterior and mediolateral directions, and path length in the anteroposterior direction were significant during stair ascending (P≤0.047, η2=0.12-0.18) as well as the range and path length in the anteroposterior and mediolateral directions and the velocity in the mediolateral direction during stair descending (P=0.046, η2=0.10-0.15), and in all functional tests variables (P=0.048, η2=0.13-0.29). The results of Bonferroni test showed a significant improvement in the variables in the post-test phase compared to the pre-test phase in the intervention group (P=0.032). No significant change was observed in any of the variables in the control group (P>0.05). The results showed a decrease in the COP parameters and an improvement in balance control during stair ascending and descending in the intervention group. Also, duration of stance phase, total time in stair ascending and descending, and the TUDS test time decreased and the stair self-efficacy was improved after exercises. 

Conclusion
The results showed that the combined exersie program improved the stair negotiation performance of older men and enabled them to control the postural sways and have better balance during stair ascending and descending. It was also associated with reduced time and increased velocity during stair ascending and descending, and increased stair self-efficacy in older men, which means improvement in stair negotiation performance. In the present study, the combined exersie program included stretching, resistance, strength, and balance exersies. Each of these components can enhance the balance and functional performance [11-14], and their combined effect on improving stair negotiation performance of older mem was confirmed in this study. This program covered different abilities required for performing daily activities [15]. Therefore, it can be expected that the program can improve the stair negotiation performance of older adults by affecting stair ascending and descending functional demands, including lower limb range of motion, strength, power, and balance control. Gavin et al. (2019), Lee et al. (2021), Handsiker et al. (2016), and Holsgaard et al. (2011) also showed the effectiveness of exercises in improving stair descending performance [16-19], which is consistent with the results of the present study. Considering the prevalence of stair climbing activities and their potential danger for the elderly and given the effectiveness of combined exercise program, these exercises are recommended for older adults.

Ethical Considerations
Compliance with ethical guidelines
This research was approved by the Ethics Committee of the University of Isfahan (Code: IR.UI.REC.1398.081) and was registered by the Iranian Registry of Clinical Trials (Code: IRCT20180101038168N1). All participants read and signed the informed consent form, and their rights were reserved during the study.

Funding
This article was extracted from Mehdi Ghaderian’s PhD dissertation, approved by the Faculty of Sports Sciences, University of Isfahan, and was funded by University of Isfahan.

Authors' contributions
The authors contributed equally to preparing this article.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
The authors would like to thank all seniors participated in this study as well as the University of Isfahan and the Faculty of Rehabilitation Sciences, Isfahan University of Medical Sciences for their cooperation in this research.



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