Sports
Pain vs Performance in Endurance: When to Push or Stop
Sports medicine physician Dr. Fernanda Lima explains how to distinguish normal training soreness from serious injuries in triathlon.
Experiencing discomfort is routine for endurance athletes, but ignoring persistent pain can be costly. Dr. Fernanda Lima details the physiology of pain, nociplastic pain risks, and how to maintain active recovery safely.
In the endurance realm, dealing with physical discomfort is an everyday reality. Between long runs, interval sessions, and rigorous triathlon schedules, runners, cyclists, and swimmers build an extraordinary tolerance for muscle soreness. The trouble starts when the fine line between physiological adaptation and structural injury is overlooked. To demystify these physical signals, sports medicine physician and rheumatologist Dra. Fernanda Lima, head of the athlete clinic at Hospital das Clínicas da USP and physician at Clínica Move, broke down sports pain mechanics on the Café com Tri podcast.
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The body's warning signal: temporary discomfort or real injury?
Pain serves as the body's protective alarm system, converting mechanical, chemical, or inflammatory stimuli into electrical impulses that travel up the spinal cord to the brain. However, not every ache felt during or after a session indicates immediate anatomical tissue damage. Transient tissue stress following strength work or a high-intensity block is expected and typically resolves within 24 to 48 hours.
The turning point for raising a red flag lies in symptom persistence and localization. Diffuse, bilateral soreness generally reflects delayed onset muscle soreness (DOMS). On the other hand, a localized pain pinpointed in a specific tendon or joint—one that worsens with consecutive sessions and lingers even at rest—signals an impending injury. Ignoring this pattern and pushing through the workload increases the risk of muscle tears, severe tendinopathies, and stress fractures.
The trap of centralized pain and nociplastic pain
When painful stimuli recur continuously without addressing the root cause, the central nervous system can slip into a state of hypervigilance. Clinically, any pain persisting beyond eight to twelve weeks is classified as chronic—a timeframe in which most biological tissues should have healed under normal recovery conditions.
In this chronic state, the neurological alarm can keep firing even after the injured tissue has completely healed. Known as nociplastic pain or centralized pain, this phenomenon stems from a dysregulation in brain neurotransmitters and inhibitory pathways. To reset this dysfunctional pattern, medical treatment frequently combines myofascial release, dry needling, motor stimulus variation, and, when indicated, low-dose neuromodulating medications to restore proper pain thresholds.
Absolute rest is outdated: the active approach to injury
The concept of complete immobilization and total bed rest has been largely discarded by modern sports medicine. Except in severe structural scenarios, such as lower-limb stress fractures (particularly in the femoral neck) or acute spinal cord compression, the standard protocol is keeping the athlete in safe motion.
Stopping completely deconditions the cardiovascular system, weakens supporting musculature, and prolongs overall tissue recovery time. The optimal strategy offloads the injured segment—such as shifting running impact to low-power cycling, pull-buoy swimming, or deep-water running—preserving aerobic fitness while the affected structure rehabilitates through a multidisciplinary approach involving physician, physical therapist, and coach.
Training load, intensity, and the law of compensation
When managing training load, excessive intensity stands out as the primary trigger for acute mechanical injuries. While high volume drives metabolic fatigue and chronic inflammation when paired with poor sleep and calorie deficits, anaerobic intervals impose extreme muscular contractions and joint impacts. At the first signs of overload, immediately trimming intensity and dialing back volume are the recommended first steps.
Another constant hazard in endurance sports is biomechanical compensation. When an athlete attempts to train with a limp or alters their gait to protect an aching ankle or knee, they inhibit crucial muscle reflexes and overload adjacent tendons. The typical outcome is a domino effect: minor foot pain quickly triggers glute overload and contralateral lower back pain, multiplying inflammatory sites.
The essential roles of strength training, sleep, and recovery
To prevent injuries and safeguard joint longevity, strength training is non-negotiable. Strong muscles and core stability absorb the repetitive impact of cyclic triathlon movements, shielding tendons and cartilage. Conversely, hypermobility and ligamentous laxity without adequate muscular support leave joints vulnerable.
In recovery, no tool or modality replaces biological foundations: quality sleep and proper nutrition remain the body's premier cellular repair mechanisms. Overusing non-steroidal anti-inflammatory drugs before long endurance events must be avoided due to the documented risks of acute kidney injury and rhabdomyolysis. Rather than chasing quick fixes, sustainable peak performance relies on transparent communication with your coach and listening closely to your body's biological cues.
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