When I was in eighth grade, I did 24 chin-ups to break the school record. I still have the certificate of achievement from the principal proudly displayed on my wall, and brag about my accomplishment from time to time. It doesn’t matter that it was so many years ago or that some tough kid has probably since broken my record. At the time, I had the strongest biceps and best-looking arms in middle school. I used chin-ups to show off to the girls in my class. I attached a chin-up bar to my bedroom doorframe so I could train at home. I did chin-ups every day. My mother even surprised me the day I broke the record with a cake featuring a chin-up bar iced on it in chocolate. I was a hero.

Here’s what I learned from doing all those chin-ups (besides the fact that it’s a great way to get attention from girls): You don’t necessarily need to lift dumbbells or use weight machines to get stronger and more defined. And neither do your clients.

To increase muscular endurance and get shapely muscles, they need to contract against a low-to-moderate resistance—60 to 80% of the maximum an individual can lift just once—with short recovery intervals between sets. To improve endurance, what matters is the amount of time the muscles are under tension. Circuit workouts are a great way to accomplish that time under tension, while also making the workout fun.>

This sprint/body-weight circuit, which can be performed outdoors or in a gym, sequences sprint running with a lower-body exercise, upper-body exercise and core exercise for a total-body muscular endurance workout. Have your clients move immediately from one exercise to the next, and perform the circuit once or twice with two minutes of rest between circuits. If you do this workout with your clients in a gym, you can substitute sprint cycling for sprint running. The sprint should be fast and challenging, but not all-out. 

 Squat Jumps

Begin in a squat position with thighs parallel to the floor and hands on your hips [1].

Jump straight up as high as you can [2]. Land with soft knees, lowering back into the squat position in one smooth motion, and immediately jump up again. Repeat for the recommended number of reps.


Assume a standard push-up position. Place your hands together so that your touching forefingers and thumbs form a diamond [1].

Lower down until your chest comes close to the floor [2].

Push back up to the starting position until your arms are straight and repeat for the recommended number of reps [3].

You can modify this push-up position by placing your knees on the floor and flexed to 90 degrees with ankles crossed [4].


Modify by doing standard push-ups with hands shoulder-width apart, or by placing your hands on a bench [5 and 6].

Pike Crunches

Lie on your back on the floor with your arms outstretched above your head and legs extended on the floor [1].

In one smooth motion, and without straining your neck, lift your torso off the floor while lifting your legs so that your arms and legs reach a pike position [2]. Slowly lower your torso and legs back down to the starting position and repeat for the recommended number of reps. You can modify this exercise by holding a stability ball between your ankles.

Squat Side Steps

Stand in a squat position with feet shoulder-width apart and thighs nearly parallel to the floor [1].

Step laterally to your left while remaining in the squat position [2]. Bring your right foot back to the starting position and continue for the recommended number of reps before switching to the other direction. Keep your chest up and back straight. To add resistance, use a resistance band or physical therapy band secured around your ankles.


Lie facedown on the floor, legs together and straight, and arms straight and extended above your head. Keep your head and neck in a neutral position [1].

Simultaneously raise your arms, legs and chest off the floor and hold this position for two seconds [2]. Slowly lower your arms, legs and chest back down to the starting position and repeat for the recommended number of reps.


Sit on the floor in a reclined position, with your legs raised off the floor. Lean back and place your hands on the floor near your hips for support [1].

Contract your abs to lift your torso, while simultaneously bringing your knees toward your chest to create a V shape (your hips should be the point of the V as you balance on your buttocks in the V position) [2]. Repeat for the recommended number of reps.

Mountain Climbers

Start in a push-up position, with your weight supported by your hands and toes. Bend your right knee and bring your right leg forward until your knee is approximately under your hip [1].

Quickly reverse the position of your legs, extending the bent right leg until it is straight and supported by your toes, and bringing your left foot forward with your hip and knee flexed [2]. Repeat by alternating your legs back and forth for the recommended number of reps.

Triceps Dips

Stand with your back to a bench, step or other immovable object. Lower yourself down to the level of the object and hold on to its edge with your arms nearly locked and legs outstretched in front of you. Keep your elbows close to your body [1].

Slowly lower your torso by bending your elbows until your elbow angle is 90 degrees or slightly less [2]. Push your torso back up by using your triceps to bring your body back to the starting position and repeat the movement for the prescribed number of reps. To make the exercise more challenging, place your feet on a bench in front of you rather than on the floor so that your entire body is elevated off the floor.

Russian Twists

Sit on the floor with your legs bent and feet anchored under an immovable object. Lean your torso back so that your torso, buttocks and thighs create a V shape. Hold your arms extended in front of you with your hands clasped [1].

Twist your torso as far as you can to your right side [2]. Hold this position for a brief moment and then twist your torso to your left side. Continue to twist to your right and left sides for the prescribed number of reps. To make the exercise more challenging, hold a dumbbell or other weighted object in your hands as you twist from side to side.

Adapted from 14-Minute Metabolic Workouts by Dr. Jason Karp. Photo credits: Jamie Dickerson of J. Dixx Photography