It takes the gastrointestinal tract about 3 to 4 hours to completely digest a full meal. Note too that the digestion phase varies between what you are eating -- for example if you ate a banana, you can exercise after 30 minutes or 1 hour after eating it but if you ate a steak, it would take you about 3 hours before it would be good to begin exercise. That said, most people find that eating trail mix mid-hike doesn't prevent them from continuing to walk, as human beings were built to eat and move.
How to: Keep your feet shoulder-width apart and your back straight. Bend your knees and lower your rear as if you were sitting down in a chair. Your weight should be evenly distributed on 3 points of your feet -- heel, outaside ball, inside ball -- that form a triangle. Your knees won't stay in line with your ankles that way, but there will be less strain on other parts of your body.  Add dumbbells once you can do 12 reps with good form.
Stand on right foot with left foot elevated and core tight. Hop 3 times then bend down and quickly walk hands out so you are in a high plank position with left foot still off ground. Do 3 push-ups, never putting left foot down. Walk hands back and stand up to return to starting position. Repeat for half the time on one side only, then switch sides.
Training to Failure. During most lifts with a moderately heavy weight, the set is completed before failure is reached. Muscles feels taxed, the sweating has begun, a few more sets are rocked, and we move on to the next exercise. This is a great way to get stronger, but is taking a set to failure an even better way? Yes and no Muscle Activation strategies during strength training with heavy loading vs. repetitions to failure. Sundstrup, E., et al. 1 National Research Center for the Working Environment, Copenhagen, Denmark 2, Institute of Sport Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark 3Department of Occupational and Environmental Medicine, Bispebjerg University Hospital, Copenhagen, Denmark. Journal of Strength and Conditioning Research. 2012 Jul;26(7):1897-903.. While training to failure — lifting until the body can't do a single more rep — recruits more muscle and triggers the body to release more strength-building hormones, it’s most effective if a very high percentage of a one rep max can be performed The application of training to failure in periodized multiple-set resistance exercise programs. Willardson, J.M. Physical Education Department, Eastern Illinois University, Charleston, Illinois 61920, USA. Journal of Strength and Conditioning Research; 2007 May;21(2):628-31. The mechanisms of muscle hypertrophy and their application to resistance training. Schoenfeld BJ. Global Fitness Services, Scarsdale, New York, USA. Journal of Strength and Conditioning Research; 2010 Oct;24(10):2857-72.. Also, sets to failure increase the opportunity for overtraining and injury, so it’s best to use this technique only occasionally and with a spotter.
It is well known that exercise in the older population may prevent several diseases [1–4]. Reduced physical activity impairs the quality of life in elderly people with Alzheimer's Disease [4], Parkinson's Disease [5], and Depressive Disorders [6]. Moreover, musculoskeletal, cardiopulmonary, and cerebrovascular decline are associated with poor physical fitness because of the cumulative effects of illness, multiple drug intake, fatigue, and bed rest [7, 8]. The effects of physical activity and exercise programs on fitness and health-related quality of life (HRQOL) in elderly adults have been widely studied by several authors [9–11]. De Vries et al. [11] conducted a meta-analysis focusing on elderly patients with mobility problems and/or multimorbidity. Eighteen articles describing a wide variety of actions were analyzed. Most used a multicomponent training program focusing on the combination of strength, balance, and endurance training. In 9 of the 18 studies included, interventions were supervised by a physical therapist. Intensity of the intervention was not reported and the duration of the intervention varied from 5 weeks to 18 months. This meta-analysis concluded that, considering quality of life, the exercise versus no-exercise studies found no significant effects. High-intensity exercise appears to be somewhat more effective in improving physical functioning than low-intensity exercise. These positive effects are of great value in the patient population but the most effective type of intervention remains unclear. Brovold et al. [7] recently examined the effects of high-intensity training versus home-based exercise programs using the Norwegian Ullevaal Model [12] on a group of over-65-year-olds after discharge from hospital. These authors based their study on the Swedish Friskis-Svettis model [13] which was designed by Johan Holmsater for patients with coronaropathy to promote their return to work and everyday activities and improve their prognoses. This model includes three intervals of high intensity and two intervals of moderate intensity, each one lasting for 5 to 10 minutes. Included in each is coordination. Exercises consist of simple aerobic dance movements and involve the use of both upper and lower extremities to challenge postural control [13]. Exercise intensity was adjusted using the Borg Rating of Perceived Exertion (RPE) Scale. Moderate intensity was set between 11 and 13, and high intensity was set between 15 and 17 on the Borg Scale.