The Triceps: Muscle Composition and the Main Reason for their Fast Fatigue

The triceps brachii, commonly known as the triceps, is a muscle group located at the back of the upper arm, opposite to the biceps. Comprising three distinct heads —the lateral, medial, and long heads— the triceps play a pivotal role in various upper body movements, particularly in extending the elbow joint. My clients often react with surprise when they go from vigorously pulling down those resistance bands to an almost sudden muscle exhaustion. Why did that happen so fast?

   Understanding the composition of the triceps muscles provides valuable insights into their function and why they tend to exhaust rapidly during intense physical activities.

Composition of the Triceps

   The composition of skeletal muscles involves two primary types of muscle fibers: Type I (slow-twitch) and Type II (fast-twitch). These fibers differ in their structure, function, and endurance capabilities. The triceps, unlike some other muscles in the body, have a higher composition of Type II muscle fibers.

Type II Muscle Fibers in the Triceps

   Type II muscle fibers, also known as fast-twitch fibers, are characterized by their ability to generate rapid and powerful contractions. These fibers are further subdivided into Type IIa and Type IIb, each with distinct properties. Research has shown that the triceps brachii predominantly consists of Type II muscle fibers, particularly the Type IIa subtype.

Fast-Twitch Nature of Triceps

   The predominance of Type II muscle fibers in the triceps equips them with the capacity for explosive strength and power. This is essential for activities requiring sudden bursts of force, such as pushing objects, lifting weights, or executing explosive movements in sports like weightlifting and sprinting. The fast-twitch nature of the triceps allows individuals to generate quick and forceful contractions, contributing to the overall efficiency of arm movements. But…

…They Fatigue Quickly

   Despite their impressive strength and power, one notable drawback of Type II muscle fibers, including those in the triceps, is their relatively quick fatigue onset. Fast-twitch fibers rely heavily on anaerobic metabolism, which produces energy without the need for oxygen. While this process is efficient for short bursts of intense activity, it leads to the accumulation of lactic acid, a byproduct that contributes to muscle fatigue.

   During high-intensity activities, such as lifting heavy weights or performing rapid repetitions, the triceps quickly deplete their energy stores, leading to the accumulation of lactic acid in the muscle tissue (1). This buildup contributes to the sensation of fatigue and muscle burn experienced during and after intense workouts. As a result, you may find that your triceps tire faster than muscles with a higher proportion of Type I muscle fibers, which are more resistant to fatigue due to their reliance on aerobic metabolism.

Training Strategies for Triceps

   Understanding the composition of triceps muscles and their predisposition to fast fatigue is crucial when designing effective training programs. Incorporating a combination of strength training, endurance exercises, and proper recovery strategies can help optimize triceps performance while minimizing the risk of overtraining and injury.

   Strength training exercises, such as triceps dips, skull crushers, cable pull-down and overhead triceps extensions, can enhance the overall strength and power of the triceps.

·         To improve endurance and delay fatigue, incorporating high repetition sets with moderate weights can be beneficial.

·         For strength and growth, multiple sets (4-6) of low or medium repetitions (4-10), with heavier weights may be the way to go for you.

   Additionally, allowing adequate rest and recovery time between triceps-focused workouts is essential to prevent overuse injuries and promote muscle recovery.

Can you train your triceps with no gym equipment?

   Of course, you can. Here are a few of the most effective body-weight exercises for the triceps:

·         Bench (or chair) dips

·         Diamond shape push ups

·         Forearm to full plank

·         Pike pushups

·         Cobra presses

(1)    Recent studies are inconclusive about lactic acid buildup being the main cause of skeletal muscle fatigue.