Athlete balancing on a path shifting between rigid and flexible states

Flexibility and Injury Risk: What Resistance Athletes Need to Know

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Jordan Keane in Health & Wellness October 2026 • 4 min read.

"Can stretching too much—or too little—impact your chance of injury? New research explores the link between flexibility and injury in endurance sports."


Injuries are an unfortunate reality for athletes, whether acute or chronic. Chronic injuries, stemming from repetitive strain, are particularly common in endurance sports. These injuries often result from a complex mix of factors, including muscle imbalances, poor posture, inadequate stabilization, old injuries, and, notably, limited flexibility.

Flexibility, often defined as the range of motion (ROM) around a joint, plays a crucial role in athletic performance and injury prevention. It enhances joint movement, cushions muscles, and helps preserve joint protection by boosting collagen production. In contrast, when a tight muscle group stretches in high stress can be too rigid, and has potential to tear or rupture.

However, flexibility needs to be sport-specific. Certain activities requiring high-force outputs may suffer from the loss of stability if overstretched. So, how much flexibility is enough, and how does it relate to injury risk in endurance sports like swimming, cycling, running, and triathlon?

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What the Data Shows

The CDC's physical activity data resources include maps, statistics, surveillance systems, and other data intended for public health practitioners and professionals. A survey of women and men examined stretching practices using response frequencies, percentages, and counts after excluding incomplete responses and people without actual sport practice. TrueSport reports that static stretching can produce small immediate decreases in speed and power for some high-performance athletes in non-endurance sports, making warm-up choices relevant to performance. These sources indicate that flexibility decisions should be informed by population data, participation patterns, and the athlete's sport demands.

Methods and Their Limits

Flexibility is commonly described through three components: passive, dynamic, and active flexibility. The available sources state that passive flexibility can facilitate development of the other two, but each component must be trained and developed separately. Flexibility training is recognized as a fitness component relevant to performance and injury prevention, yet the AOSSM tip sheet cautions that evaluating an athlete's overall flexibility can obscure the more relevant requirements of a particular sport and joint. A more useful assessment therefore considers sports-specific and joint-specific flexibility rather than relying only on a general measure.

Early Injury-Relationship Research

A cross-sectional study examined possible relationships between lower-limb flexibility and injury history in resistance modalities. Its population included participants in cycling, running, swimming, and triathlon. The study's design focused on associations between existing flexibility and injury history rather than establishing that flexibility caused or prevented injuries. This work helped frame flexibility as a question relevant across several endurance and resistance modalities.

Decoding the Flexibility-Injury Puzzle in Endurance Sports

Athlete balancing on a path shifting between rigid and flexible states

A recent study published in the Revista Brasileira de Ciências do Esporte investigated the relationship between lower limb flexibility and injury incidence across four endurance disciplines: cycling, running, swimming, and triathlon. The researchers aimed to determine if athletes with a history of injuries exhibited reduced flexibility compared to their non-injured counterparts.

Eighty athletes (20 from each sport) participated in the study. All had been training for at least a year, committing a minimum of four hours per week to their respective sport. The study involved questionnaires detailing training history and injuries, followed by goniometric assessments to measure the flexibility of key lower limb joints: hip (flexion, extension, abduction, and adduction), knee (flexion), and ankle (plantar flexion, dorsal flexion, abduction, and adduction).

  • Cyclists and Triathletes Train Harder: Cyclists and triathletes generally logged more training hours than runners and swimmers.
  • Many Lack Comprehensive Support: While all athletes had a coach, only 24% had access to resources like nutritionists, physical therapists, or sports psychologists.
  • Knee Injuries are Common: Across all sports, knee injuries were frequently reported. Triathletes reported the highest number of injuries overall, followed by swimmers, cyclists, and runners.
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Current Sport-Specific Evidence

Recent research has continued to examine flexibility in athletes from distinct strength-related and endurance-related sports. A 2025 comparative analysis focused on goniometric indicators in kettlebell lifting and arm wrestling athletes and referenced earlier work involving running, cycling, swimming, and triathlon. A 2024 study analyzed the functional kinetic performance of the lower limbs in amateur runners from Gurupi, Brazil, with research conducted at the Clinical School of Physiotherapy of UnirG. Together, these studies illustrate the use of sport-specific movement and range-of-motion measures rather than treating all athletes as one group.

The results revealed intriguing connections between flexibility and injury, challenging common assumptions. The data suggested the influence of flexibility in athletic injury history. The relationship between flexibility and injury differs across resistance modalities.

The Takeaway: Flexibility is Personal

The study underscores that flexibility's role in injury risk isn't straightforward. While reduced flexibility can increase risk, overdoing it may cause issues depending on the athlete's sport. Each resistance sport seems to respond differently to flexibility. It also calls for a personalized approach to training. Athletes and coaches should consider sport-specific demands, individual biomechanics, and training volume when designing flexibility programs.

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Interpreting Mixed Evidence

A 2024 review reports high heterogeneity in both research methods and findings concerning how flexibility training increases range of motion. It also notes that scientific conclusions are based mostly on functional observations, while studies examining underlying physiology are less common. A separate 2024 case study used sit-and-reach tests before and after an exercise program and analyzed results with paired and unpaired t-tests. These sources support cautious interpretation: observed flexibility changes do not automatically resolve the physiological explanation or establish a universal performance effect.

A Changing Endurance Landscape

Future flexibility and injury-risk research will develop within an endurance-sports landscape marked by rising participation. RaceFinder reports continued growth in road races, trail runs, triathlons, and cycling events, with major races regularly selling out months in advance. PEZ Cycling News describes a 2026 survey of world-class endurance coaches examining emerging approaches to preparation, recovery, and performance optimization. Other reported trends emphasize technological advances, environmental awareness, and changing lifestyle preferences in outdoor endurance sports.

From Testing to Practice

A case study involving 460 participants examined flexibility as a component of physical fitness related to athletic performance and general health. The study compared athletes and non-athletes and evaluated the effect of training on flexibility. Its observational case-study design provides a real-world comparison, but it does not by itself establish that training caused every observed difference. A separate 2026 coaching case study describes addressing metabolic flexibility pragmatically through periodized nutrition and endurance-performance planning, highlighting the practical role of individualized decisions.

About this Article -

Written with AI assistance from published research, and reviewed by the Mystum team. See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.rbce.2018.05.003, Alternate LINK

Title: Relações Entre Flexibilidade De Membros Inferiores E Índice De Lesões Em Modalidades De Resistência

Subject: Physical Therapy, Sports Therapy and Rehabilitation

Journal: Revista Brasileira de Ciências do Esporte

Publisher: FapUNIFESP (SciELO)

Authors: Matheus Silva Norberto, Enrico Fuini Puggina

Published: 2019-07-01

Everything You Need To Know

1

What exactly is flexibility, and why does it matter for athletes?

Flexibility refers to the range of motion around a joint. It's important because it affects athletic performance and injury prevention by enhancing joint movement, cushioning muscles, and helping preserve joint protection by boosting collagen production. However, excessive flexibility can reduce stability which is critical in high-force output activities. Insufficient flexibility can cause muscles to become too rigid increasing the risk of tears or ruptures. Therefore, it is key to understand the balance required for your body and sport.

2

What are chronic injuries, and why are they so common in endurance sports?

Chronic injuries are injuries that develop over time due to repetitive strain. They're significant because they're common in endurance sports and can result from various factors like muscle imbalances, poor posture, inadequate stabilization, old injuries, and limited flexibility. These injuries can significantly impact an athlete's ability to train and compete, highlighting the importance of preventative measures like appropriate flexibility training, proper warm-up techniques, and addressing underlying biomechanical issues.

3

What is the Revista Brasileira de Ciências do Esporte study about, and why is it relevant?

The Revista Brasileira de Ciências do Esporte study examined the relationship between lower limb flexibility and injury incidence in endurance sports like cycling, running, swimming, and triathlon. It is important because it challenges assumptions about flexibility and injury. The study's findings highlight the complex interplay between flexibility, training volume, and sport-specific demands, emphasizing the need for personalized training programs that consider individual biomechanics and injury history.

4

What are goniometric assessments and why are they important for athletes?

Goniometric assessments are ways to measure the flexibility of joints, specifically the lower limb joints like the hip (flexion, extension, abduction, and adduction), knee (flexion), and ankle (plantar flexion, dorsal flexion, abduction, and adduction). These measurements are important because they can help assess an athlete's range of motion and identify any limitations that may contribute to injury risk. By tracking changes in flexibility over time, athletes and coaches can tailor training programs to address specific needs and prevent potential problems. Using goniometric assessments helps to quantify the qualitative aspects of flexibility.

5

What is the main takeaway regarding flexibility and injury risk?

The study suggests that the relationship between flexibility and injury is not straightforward and can vary depending on the sport. This is important because it means that there's no one-size-fits-all approach to flexibility training. Athletes and coaches need to consider sport-specific demands, individual biomechanics, and training volume when designing flexibility programs. This personalized approach can help optimize performance and minimize the risk of injury.

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