Interventions based on resistance training have been shown to counteract muscle disuse and therefore combat muscle strength and muscle mass loss, with positive effects on physical functioning, mobility, independence, psychological well-being, and quality of life. Unfortunately, a low percentage of older adults meet international recommendations on resistance training probably due to fear, health concerns, pain, fatigue, or lack of social support. There is a need for evidence-based guidelines and recommendations for resistance exercise for older adults to safely and gradually introduce this type of training into their routines. However, there is no “average” older adult, and so it is impossible to provide a single recommendation that is fully representative, especially across age groups. All individuals respond differently to resistance training, and progression should be closely monitored to be able to individually adjust the training program; consequently, different methods available for assessing muscle strength and physical function that serve to analyze the effectiveness of interventions are discussed in this chapter. New strategies used in combination with resistance training in older adults are also addressed, in order to provide novel insights regarding the resistance strength training in this population group.