Here are some rules of thumb that will help guide you in your fitness training:
1. Cardio, Cardio, Cardio. Your cardio intensity should be enough that you are breathing out of your mouth. This is essential if you want oxygen to your brain and muscle stamina at exactly the right moment.
2. Strength Training. Select strength training that encourages multi-joint movement over bulk for example free weights, elastic stretch bands, pilates are better for a rider than machines which support your body for you while targeting only one or two muscles.
3. Repititions. High repetitions with low weights are only good if you work the muscles to exhaustion. You won’t get bulky doing this, but will get incredible stamina. Also, if you need to be doing strength training a minimum of twice a week or you won’t progress.
4. Don’t let your muscles tighten. Work muscles you use for riding in a fuller range of motion than you do riding so they do not shorten and tighten.
5. Glutes & Thighs. Work your glutes and outer thighs to support your hips so you can sit deep and avoid lower back strain.
6. Shoulders. Work your shoulders — especially women.
7. Work your core daily. Two minutes of core exercises every day is better than 15 minutes or more once or twice a week. A great goal is a total of 100 to 200 cumulative repetitions of a variety of core exercises daily. Remember your core includes your sides and back too. Most riders do not work the back enough.
8. Posture. Be mindful of posture at all times, no matter what you’re doing. Engage your core through every exercise, and every task and moment of your day if you want to develop beautiful posture that maintains itself without effort.
9. Work your body evenly. It’s important not to do a lot of activity which uses your body unevenly, such as racquet sports.
10. Breathe. Teach yourself to breathe into your abdomen, and use that deep breathing when you exercise. It will carry over to your riding, provide your body with more oxygen in performance, and also relax both you and your horse.
11. Rest & Recover. Give your body a day off. You do it for your horses. All athletes build rest into their schedule because over training and overwork breaks you down.