A significant majority of athletes, regardless of their level of competition, seek medical attention for musculoskeletal injuries. These injuries, affecting muscles, tendons, ligaments, bones, and cartilage, often occur due to weaknesses in the extracellular matrix (ECM) of the body. In simpler terms, the ECM is like the steel bars in reinforced concrete that give strength and flexibility to the body's structures, particularly bones. Strengthening the ECM can potentially reduce the risk of sports-related injuries. Additionally, the ECM plays a vital role in performance by improving the rate at which force is developed, which is a key determinant of speed and power.
The Dynamic Nature of the ECM and Its Functions
For a long time, the ECM was considered a static gel-like substance that merely held tissues together. However, recent experiments have challenged this notion, revealing the ECM to be a dynamic tissue that is crucial for proper musculoskeletal function. In the context of athletes, the ECM serves two primary purposes:
- Efficiently transmitting forces to maximize speed and performance, and
- absorbing impact to prevent injuries.
Muscle and tendon ECM primarily contribute to the first role, while ligaments, cartilage, and bone ECM are involved in the second role. In the following sections, we will explore how exercise and nutrition can optimize both of these functions.
Influence of Collagen and Cross-Linking on ECM Functionality
The functionality of the ECM depends on the quantity and cross-linking of collagen, as well as the water content within the tissue. While the water content remains relatively stable during training, making the ECM stiffer and stronger requires an increase in collagen quantity or the number of cross-links that bind collagen proteins together. Cross-linking can occur through enzymatic means (involving specific enzymes like lysyl oxidase and prolyl-4-hydroxylase) or non-enzymatic means (involving cross-links derived from glucose). In general, enzymatic cross-links are beneficial and can be regulated through exercise and nutrition, while glucose-derived cross-links are detrimental and can lead to negative consequences associated with conditions like diabetes, such as high blood pressure, an increased risk of tendon rupture, and cataracts.
Optimizing Performance: High-Velocity Movements and Plyometrics
To optimize speed and power performance, coaches incorporate high-velocity movements with a plyometric element into training. This type of training has two effects on the ECM:
- It increases the amount of collagen and cross-linking in the ECM of muscles
- It enhances cross-linking in the ECM at the muscle end of tendons.
As a result, force can be transmitted more rapidly from muscles to bones, resulting in improved speed and power.
Preventing Muscle Injuries: Slow Movements and Protective Mechanisms
To prevent muscle injuries, coaches and physical therapists employ slow movements, such as heavy weight training, slow eccentric movements, or prolonged isometric holds. This type of training has slightly different effects on the ECM:
- It still increases collagen quantity and cross-linking in the ECM of muscles, but unlike fast movements,
- It reduces cross-linking in the ECM at the muscle end of tendons.
This reduction in stiffness in the tendon's muscle end acts as a protective mechanism, safeguarding the associated muscles from injury.
Advancements in Injury Prevention for Ligaments, Cartilage, and Bones
While coaches have some tools to enhance muscle and tendon performance and reduce injury rates, there are fewer options available for preventing injuries in ligaments, cartilage, and bones. This limitation primarily stems from our incomplete understanding of how these tissues respond to loading and nutrition. However, recent advancements offer hope for a new range of techniques to prevent stress fractures and slow down the degeneration of ligaments and cartilage.
Gelatin, Collagen, and Injury
A significant breakthrough came from research involving both rodents and humans, which demonstrated that short loading protocols (consisting of 5 and 40 loads) with intervals of over 6 hours of rest were sufficient to maximize bone synthesis rates. Likewise, our own research revealed that collagen synthesis in ligaments reached its peak with short periods (5-10 minutes) of exercise separated by 6 hours of rest. These findings indicate that, unlike muscle adaptation that continues throughout exercise, our ECM only responds to the stimulus for a limited duration before cellular activity decreases. Any exercise beyond this period only leads to mechanical fatigue and damage, without providing further stimulus for adaptation and increased strength.
Incorporating Protective Sessions and Enhancing ECM Production
Based on these findings, it is recommended to include brief loading sessions (lasting 5- minutes) that target the tendons, ligaments, bones, or cartilage relevant to a particular sport. For instance, runners can incorporate jump rope exercises, basketball players can engage in bench step-ups, and baseball/water polo/cricket players can focus on rotator cuff exercises. It is crucial to schedule these protective sessions at least 6 hours away from other training sessions, whenever possible. By doing so, these sessions stimulate ECM production, thereby reducing the likelihood of repetitive stress injuries to bones, ligaments, tendons, and cartilage.#
Optimizing ECM Production Through Nutrition: Gelatin Study
Moreover, we now understand that ECM production can be enhanced through nutrition. In our most recent study, we combined intermittent exercise with gelatin, a food source rich in amino acids found abundantly in collagen (Shaw et al., 2017). In a randomized double-blind cross-over design study, participants were given either a placebo, 5 grams, or 15 grams of gelatin mixed with approximately 500 ml of blackcurrant juice rich in vitamin C (providing around 50 mg of vitamin C). We analyzed the appearance rate of amino acids and collagen production within the first 4 hours of the intervention.
To boost collagen synthesis, participants performed 6 minutes of jump rope exercise one hour after consuming the supplements. Consistent with the significance of short loading periods for collagen synthesis, the 6-minute jump rope session doubled collagen synthesis in both the placebo and 5g gelatin groups. Furthermore, when participants consumed the higher gelatin dosage (15g), collagen synthesis increased twofold compared to the collagen synthesis achieved through jump rope exercise alone.
Incorporating Gelatin for Injury Prevention and Recovery
For coaches and athletes, this means that consuming gelatin one hour before a 5-minute protective session, scheduled at least 6 hours away from other training, can enhance the health of bones, cartilage, tendons, and ligaments. This approach aids in injury prevention and expedites the return to play.
The Future of ECM Research and its Impact on Athletes
Ongoing research in the field of ECM holds great potential for improving athletic performance and minimizing injuries. As our understanding of the ECM continues to evolve, new techniques and strategies can be developed to optimize athletic performance and ensure the well-being of athletes.
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- Shaw G, Lee-Barthel A, Ross ML, Wang B, Baar K. 2017. Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis. Am J Clin Nutr 105: 136-143.