Jim Levy

Cardio and full-body resistance training.

Up to 10 minutes. 3 days a week.

Planned heart-rate-guided intervals help control intensity in support of your fitness or sport-specific goals, building endurance and strength-endurance through consistent training and steady progression.

Interactive anatomical model showing muscle groups involved in weighted jump rope.

See muscles trained in the Human Atlas

Lower body

Calves, quadriceps, hamstrings and glutes generate each jump and help absorb each landing.

Upper body and trunk

Shoulders, forearms and grip control the rope, while the abdominals, obliques and back stabilize posture.

Adapted from Human Atlas and BodyParts3D 4.0

Jim Levy jumping with a five-pound weighted rope on a purple cushioned mat.

Jim during a high-intensity interval with a five-pound rope.

Apple Watch displaying a heart rate of 165 bpm during the fifth weighted-rope work interval using a five-pound rope.

Apple Watch guides interval timing and heart-rate intensity.

Sample interval data, February 6 workout

3 lb: 149 bpm average, 156 bpm peak

4 lb: 149-150 bpm average, 164 bpm peak

5 lb: 154 bpm average, 167 bpm peak

Review the workout data

Jump Anywhere. Train for Life.

One of the many benefits of jumping rope is the ability to choose your surface. To sustain your training over a lifetime, JumpIron recommends a flexible roll-out mat rated for impact protection for every workout.

General fitness

Cardiovascular conditioning and whole-body strength-endurance in one brief, structured workout.

Competitive athletes

Time-efficient conditioning that leaves more time for sport-specific training and practice.

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Jim’s letter was published in the Letters section of The Economist July 25th 2026:

Working out

“How little exercise can you get away with?”, you asked (Well Informed, July 11th). The piece offered inactive readers an answer they may be too eager to hear. Running for a bus or hurriedly climbing steep stairs may briefly raise the heart rate, but incidental exertion should not be confused with a structured exercise programme that progressively develops cardiovascular fitness, muscular strength, power, balance, co-ordination and mobility.

Your article cited the WHO guidelines that call for muscle-strengthening activities on at least two days a week. An occasional dash for a bus or climb up steep stairs is not a substitute for that. Nor should physically demanding industrial labour automatically be treated as health-promoting exercise. Physical exertion is not synonymous with exercise training, which is planned, structured and progressive.

JIM LEVY

Certified personal trainer

Los Angeles

Reproduced with permission.

Jim developed the weekly Karate & Fitness class for blind and low-vision adults at Braille Institute Los Angeles in January 2024 and continues to lead it as a volunteer instructor.

This experience has sharpened Jim’s approach to precise verbal instruction, safe class organization, gradual progression, and adapting challenging exercises to a wide range of abilities.

JumpIron is an independent business and is not sponsored or endorsed by Braille Institute.