In untrained men, adding isolated arm exercises to a workout routine may cause the muscles that straighten the elbow to grow more in certain areas than the muscles that bend the elbow, while the...

Pro

Against

Mechanism

Synthesis from 1 study

How it works

When untrained men add isolated triceps extensions to their workouts, the back of their arms get extra tension that compound lifts don’t fully provide, making the triceps grow more in certain spots and making the whole arm look bigger when flexed — but the biceps don’t grow any more with extra...

Most probable mechanism

In Simple Terms

When untrained men do arm exercises that only bend or straighten the elbow — like triceps extensions — the back of the arm gets more direct tension than when they do compound moves like push-ups. This extra tension makes the triceps grow more in certain spots, which makes the whole arm look bigger when flexed, even though the biceps grow the same no matter what kind of exercise they do. This is seen in the study that found arm circumference increased more when single-joint exercises were added, even though strength gains were the same (10.4081/ejtm.2018.7827).

Causal chain

Single-joint elbow extension exercises apply direct mechanical tension to the triceps brachii that is distinct from the indirect activation during multi-joint movements, leading to localized muscle fiber strain patterns not fully replicated by compound lifts (10.4081/ejtm.2018.7827)

Supported by evidence

which leads to

This distinct mechanical loading pattern in the triceps activates intracellular signaling pathways, such as mTOR, that increase muscle protein synthesis specifically in the elbow extensors, contributing to regional hypertrophy (10.4081/ejtm.2018.7827)

Supported by evidence

which leads to

The biceps brachii, which are heavily activated during multi-joint exercises like pull-ups and rows, reach a saturation point in growth stimulation, so additional single-joint flexion exercises do not further increase their hypertrophy, while the triceps continue to respond to isolated overload (10.4081/ejtm.2018.7827)

Supported by evidence

which leads to

Accumulated regional hypertrophy in the triceps brachii increases the overall cross-sectional area of the upper arm, which is reflected as a greater increase in flexed arm circumference compared to groups performing only multi-joint exercises (10.4081/ejtm.2018.7827)

Verified by multiple studies

Evidence from Studies

Supporting (1)

Community contributions welcome

Does the addition of single joint exercises to a resistance training program improve changes in performance and anthropometric measures in untrained men?

Randomized Controlled Trial

Human

2018 Nov 2

Contradicting (0)

Community contributions welcome

No contradicting evidence found

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

Source Study

Does the addition of single joint exercises to a resistance training program improve changes in performance and anthropometric measures in untrained men?

Score: 52

DOI: 10.4081/ejtm.2018.7827

Similar Assertions

In untrained young men, adding isolated arm exercises to a full-body weight training program for 8 weeks led to a slightly larger increase in arm size compared to full-body training alone, but there was no difference in overall strength improvements.

82%

When young men who haven't trained before do either multi-joint exercises (like curls) or single-joint exercises (like bicep curls) for 10 weeks, their arm muscles grow by about the same amount - there's no meaningful difference between the two types of workouts.

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If young men who haven't exercised before do either multi-joint exercises (like pull-ups) or single-joint exercises (like bicep curls) for 10 weeks, their arm strength increases by about the same amount - neither type of exercise is clearly better than the other.

76%

When young men who don't work out start doing arm exercises twice a week for 10 weeks, their biceps get about 6% bigger.

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Doing bicep curls only halfway up (keeping the arm stretched) might make the lower part of your bicep grow a tiny bit more than doing full curls, but the difference is very small.

76%