Rucking, walking while carrying a weighted backpack, combines cardiovascular effort with resistance training. Originating in military training, where soldiers carry heavy packs over long distances, it is now embraced by the general public for fitness. Fitness enthusiasts often question whether this weighted walk provides enough resistance to build muscle (hypertrophy), or if its benefits are limited to endurance. This article explains the physiological mechanisms that allow rucking to promote muscle growth and details how to structure a routine for maximum muscle-building benefit.
How Carrying Weight Stimulates Muscle Growth
Muscle growth is primarily triggered by mechanical tension, the physical stress placed upon muscle fibers during activity. When rucking, the added weight significantly increases the overall load compared to normal walking. This amplified load forces muscle fibers to generate more tension and recruit a greater number of motor units to complete each step.
This continuous, low-level resistance creates a prolonged state of “time under tension.” Unlike traditional weightlifting where tension is intense but brief, rucking sustains moderate tension over an extended period. This sustained mechanical stress causes microscopic damage (micro-tears) within the muscle fibers. The subsequent repair process, fueled by protein synthesis, leads to muscle fibers increasing in size and strength.
While heavy, short-burst resistance training maximizes muscle size, rucking provides a unique stimulus blending strength and endurance. The level of resistance typically used in rucking is usually far below the maximum a person could lift, so it does not induce the same high-threshold muscle fiber recruitment as heavy strength training. Instead, it promotes muscular endurance adaptation and modest hypertrophy, especially for individuals new to resistance exercise or those using heavier loads.
Primary Muscle Groups Engaged
Rucking is a full-body, compound exercise that engages numerous muscle groups simultaneously to propel the body and stabilize the weighted load. The primary focus falls on the lower body, which provides locomotion. The gluteal muscles and hamstrings are heavily recruited for hip extension, driving forward propulsion, especially when moving uphill or over uneven terrain.
The quadriceps, located on the front of the thigh, extend the knee during the walking stride and act eccentrically to stabilize the knee joint, particularly when descending hills. The calves (gastrocnemius and soleus) work continuously to provide ankle stability and assist in pushing off the ground. The constant demand for stability from the added weight places a significant workload on the core muscles.
The core stabilizers, including the transverse abdominis and obliques, contract continually to prevent excessive rotational forces and maintain balance. The erector spinae muscles maintain an upright posture and prevent the torso from collapsing forward under the load. The upper back and trapezius muscles support the weighted pack straps, stabilizing the upper body against the downward force.
Training Parameters for Maximum Hypertrophy
To shift rucking’s benefits toward muscle hypertrophy, specific training variables must be manipulated. Weight selection is the most important factor, as the load must be sufficient to provide a significant mechanical tension stimulus. A weight range of 20% to 35% of the individual’s body weight is recommended for those seeking a strength and muscle-building focus.
For example, a person weighing 180 pounds should aim to ruck with a pack between 36 and 63 pounds to maximize resistance. The duration and distance should be shorter than traditional endurance rucking to maintain higher intensity and preserve muscle fiber integrity. Rucks focused on muscle building should be limited to 60-90 minutes and prioritize uneven terrain or inclines, which force greater muscle activation.
Increasing the weight or intensity over time is necessary to ensure progressive overload, a fundamental principle of muscle growth. Progression involves increasing the pack weight by approximately five pounds every few weeks, or increasing the speed or steepness of the route. Integrating bodyweight movements while wearing the pack (such as squats, lunges, or step-ups) can further intensify mechanical tension on the lower body, providing a more direct stimulus for muscle fiber recruitment and hypertrophy.