What is the difference between partial range of motion training at long vs. short muscle lengths?

Training at long muscle lengths involves performing repetitions in the stretched portion of the movement, which tends to promote more significant hypertrophy, especially in distal muscle areas. Conversely, partials focusing on short muscle lengths (like near the lockout) result in less overall growth.

Are partial reps considered 'cheating' in training?

Traditionally, partial reps focusing only on the top half of a movement might have been seen as cheating. However, performing partials specifically at long muscle lengths (e.g., the stretched bottom portion of a curl or fly) can be a highly effective strategy for muscle growth, particularly for distal muscle sites.

Which parts of the muscle benefit most from specific range of motion training?

Proximal muscle sites (closer to the body's center, e.g., near the hip or shoulder) show similar growth regardless of training range of motion. However, distal muscle sites (further from the center, e.g., lower quads or upper triceps) show significantly greater growth when trained through long muscle lengths or a full range of motion that includes long muscle lengths.

How can I apply partial range of motion training to my workouts like dumbbell flies?

For exercises like dumbbell flies, focus on the descending (stretch) phase and perform repetitions up to the point where significant tension is maintained but you are not fully shortening the muscle. This emphasizes the long muscle length portion and can lead to a strong hypertrophic stimulus, as described in the video.

Does not locking out reps in exercises like tricep extensions impact muscle growth?

Studies suggest that skipping the lockout phase (short muscle length portion) in exercises like tricep extensions and focusing on the mid-to-lower range might not negatively impact hypertrophy and could even lead to greater growth, especially if it ensures continuous tension on the muscle.

Key Moments

Partial Range of Motion Training Might Increase Muscle Growth (If You Do the Right Type of Partials)

Stronger By Science

Sports4 min read22 min video

Feb 18, 2022|3,602 views|150|14

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Key Moments

TL;DR

Partial range of motion training can boost muscle growth, especially when focusing on long muscle lengths, such as excluding lockouts.

Key Insights

Full range of motion is not always superior for hypertrophy; the key is muscular tension, particularly at long muscle lengths.

Partial range of motion training can be as effective, or even more effective, than full range of motion for muscle growth if performed correctly.

The effectiveness of partial reps depends heavily on the portion of the range of motion trained; long muscle lengths are generally more beneficial than short muscle lengths.

Partial reps performed in the short muscle length range (like locking out every rep) tend to yield less hypertrophy, especially in distal muscle regions.

Muscle growth is not uniform across the entire muscle; distal regions (further from the torso) often benefit more from training at long muscle lengths compared to proximal regions.

While more direct research is needed, evidence suggests that excluding the lockout (short muscle length) portion of a lift might be beneficial or at least not detrimental to hypertrophy.

RETHINKING FULL RANGE OF MOTION TRAINING

The common belief that full range of motion (ROM) is paramount for muscle hypertrophy is being challenged. The core benefit often attributed to full ROM might simply be ensuring that the exercise includes periods of significant muscular tension, particularly when the muscle is lengthened. The specific degree of joint movement or total angular displacement may be less critical than training through the portion of the ROM that involves longer muscle lengths.

DEFINING PARTIAL RANGE OF MOTION TRAINING

When discussing partial range of motion (ROM) training, it's crucial to distinguish between different types. Traditional 'partials' often involve movements like half squats or bench presses where the range is limited, frequently focusing on the top half of the movement, which corresponds to shorter muscle lengths. This contrasts with partials performed through the bottom half of the movement, which engages longer muscle lengths and seems to yield superior results for hypertrophy.

STUDY 1: LONG VS. SHORT MUSCLE LENGTH PARTIALS

A study by Pedrosa et al. investigated the effects of different ROMs on knee extensions in untrained women. Groups trained with full ROM, partial ROM at long muscle lengths (bottom half), partial ROM at short muscle lengths (top half), or a variable ROM. The results indicated that partial ROM at long muscle lengths produced the most favorable hypertrophy response, outperforming even full ROM and other partial variations, especially at distal muscle sites.

STUDY 2: REPLICATING FINDINGS IN ELBOW FLEXORS

A subsequent study by Sato et al. examined unilateral preacher curls, comparing partial ROM at long muscle lengths versus short muscle lengths. This research reinforced previous findings, showing significantly greater hypertrophy in the long muscle length group. The difference was more pronounced at distal measurement sites along the muscle, suggesting that training at longer muscle lengths is particularly important for growth in those specific areas.

ISOMETRIC TRAINING AND REGIONAL HYPERTROPHY

Further evidence comes from systematic reviews on isometric training, which show that holding contractions at long muscle lengths promotes greater hypertrophy than at short muscle lengths. Moreover, research indicates that hypertrophy effects are not evenly distributed. Proximal muscle regions (closer to the torso) tend to grow similarly regardless of ROM, but distal regions (further from the torso, like the horseshoe of the tricep or lower quads) benefit significantly more from training that includes long muscle lengths.

IMPLICATIONS FOR TRAINING PRACTICES

These findings suggest that while full ROM isn't necessarily detrimental, focusing partial reps on the long muscle length portion of a lift—essentially avoiding the lockout or top range where muscle length is shortest—can be highly effective for hypertrophy. This approach may yield comparable or even superior muscle growth compared to traditional full ROM training, especially for developing distal muscle bellies.

PERSONAL APPLICATION AND PERCEPTION

Some individuals incorporate partial ROM training, particularly at long muscle lengths, as a way to push sets beyond failure or to focus tension on specific muscle areas. This might appear unconventional to observers, who may perceive it as 'cheating.' However, the underlying principle is to maximize tension and stimulus in muscle-lengthening positions, which research now supports as a potent driver of hypertrophy, particularly for distal muscle growth.

THE ROLE OF DISTAL MUSCLE GROWTH

The differential growth response between proximal and distal muscle sites is a key takeaway. While all parts of a muscle may experience some stimulus, the distal portions, which contribute significantly to the visual 'size' and aesthetics valued in bodybuilding, are particularly sensitive to training at long muscle lengths. Therefore, strategically employing partials in this range could be crucial for maximizing overall muscle development.

Mentioned in This Episode

●Organizations

Optimizing Training for Muscle Growth: Key Principles

Practical takeaways from this episode

Do This

Focus on training through the portion of the rep that involves muscular tension and long muscle lengths.

Consider partial range of motion training specifically at long muscle lengths for potentially enhanced hypertrophy.

Utilize partials at long muscle lengths to target distal muscle sites, which are crucial for overall muscle size.

Incorporate techniques like "constant tension training" by cutting out the lockout portion of the rep if it doesn't maintain tension.

When performing exercises like dumbbell flies, aim for a range of motion that maintains tension without fully lengthening or shortening the muscle.

Don't discount partial range of motion training, especially if it allows for increased training volume or focus on specific muscle lengths.

Avoid This

Do not assume all partial range of motion training is equivalent; the muscle length at which you train matters significantly.

Avoid partial range of motion training exclusively in the short muscle length portion of the movement, as it tends to yield less growth.

Do not neglect the potential benefits of training at long muscle lengths, even if it appears to be 'cheating' by traditional standards.

Be aware that the benefits of range of motion might not be evenly distributed across all parts of a muscle; distal sites are more sensitive to muscle length.

Comparison of Hypertrophy Responses Based on Range of Motion and Muscle Length

Data extracted from this episode

Training Group	Average Hypertrophy Response	Distal Site Hypertrophy Response
Partial ROM at Long Muscle Lengths (Pedrosa study)	Best overall	Best
Full ROM (Pedrosa study)	Solid	Good (involved long muscle lengths)
Variable ROM (Pedrosa study)	Solid	Good (involved long muscle lengths)
Partial ROM at Short Muscle Lengths (Pedrosa study)	Significantly less	Noticeably less
Partial ROM at Long Muscle Lengths (Sato study)	2.6x greater than short ROM partials	Increased magnitude of difference at distal sites
Partial ROM at Short Muscle Lengths (Sato study)	Lower	Lower

Common Questions

Not necessarily. While full range of motion can be effective, the key factor might be training through the portion of the movement that involves muscular tension at long muscle lengths. Partial range of motion training, specifically emphasizing long muscle lengths, can yield comparable or even superior results.