Sergeant Ken Weichert could teach you a thing or two about carrying heavy loads. The master Army trainer humped 75 pounds of gear in 125-degree heat in both Gulf Wars and credits ruggedized abdominal and back muscles for keeping him upright. That's why Weichert now emphasizes core training as part of his boot-camp-style fitness classes in the Bay Area. "It's all about posture," explains the 38-year-old hiker, who also leads backpacking trips (most popular: Operation Summit Whitney). "Your core muscles stabilize the spine, which lets you maintain proper posture. This prevents injury, improves balance, and keeps your pack weight on your hips instead of your shoulders." Plus, a solid core provides a base of strength for the entire body, enabling you to put more power into each step with less effort. Perform Weichert's workout 3 to 5 times a week. Start with 10 repetitions and gradually build to 50 for each exercise. Every 10th rep, hold for 10 seconds to check your form; proper form better targets the muscles you want to strengthen and prevents injury.
Lie on your stomach, arms out to side and bent at the elbows. Squeeze your glutes and lift your legs a few inches off the ground. Lift your chest slightly while you look straight ahead. Hold this position as you move your arms about 6 inches back and forth. Keep your butt tight to prevent back injury and to keep core muscles engaged. Works: entire back, glutes, quads
Russian Twist With Medicine ball
Set a decline bench at a 45-degree angle. Sit at the top holding a 6-pound medicine ball (or 2/3 gallon jug of water) near your upper chest. Engage the abdominals and slowly drop halfway down until your torso is perpendicular to the bench. Twist to the right, back to center, then to left as if you were drawing a semi-circle with the ball. Repeat. As your strength increases, hold the ball six inches from your chest, then with fully extended arms (don't lock your elbows). Works: entire abdominal area
Push-Ups To Plank
Here's a simple twist on the old standby. Do as many push-ups as you can until muscle failure, then go immediately into a plank hold by resting on your forearms and hold for 30 seconds. Build to 45 second, then 60. Keep your glutes and abs clenched to ensure the core muscles are active. Works: chest, arms, back, abdominals, glutes, thighs