Numbness in Your Arm? It Might Not Be Carpal Tunnel. Sciatica Down Your Leg? Here’s What Actually Helps.

You have numbness running down your arm. Your grip feels weak. Someone says carpal tunnel. You have shooting pain down your leg. Your calf goes numb. Someone says sciatica. Both of those might be right. But in a lot of cases, the source is not where the symptoms are — it is in your spine.

Cervical radiculopathy — a nerve issue in your neck — sends pain, numbness, and weakness into your arm and hand. It gets misdiagnosed as carpal tunnel constantly. Lumbar radiculopathy sends the same symptoms into your leg and foot. Both involve nerve irritation at the spine, and both respond to the same principle: get the nervous system to calm down.

One of the most effective ways to do that is aerobic exercise. But not just any aerobic exercise.

Walking Is Good. Is It Good Enough?

If you have radiating nerve pain and someone tells you to walk more, that is not bad advice. Walking is better than sitting. Movement is better than rest. But here is the question: is a flat walk actually reaching the intensity your nervous system needs to change how it processes pain?

For most people, the answer is no.

The research shows that exercise-induced pain relief — called exercise-induced hypoalgesia — requires a minimum intensity threshold to activate. That threshold is approximately your first ventilatory threshold, or VT1 — the point where your breathing starts to pick up and holding a conversation becomes just slightly harder. Below that, you are moving, but you are not triggering the neurochemical changes that actually reduce pain (Naugle et al., The Journal of Pain, 2012). If you have heard of zone 2 training — it has gotten a lot of attention lately — VT1 is essentially the same thing. It is the intensity where your aerobic system is working hard but sustainably. You do not need a lactate monitor to find it — but most people cannot reliably find it on their own either. We use graded treadmill test protocols to identify your thresholds precisely and prescribe the exact intensity that works for you. We have done enough of these to know what the numbers should look like — and when they do not, that tells us something too. Finding your threshold is part of what we do at your evaluation.

A flat walk at a comfortable pace does not get most people to VT1. An inclined treadmill walk does. A rower does. A ski erg does. A bike with resistance does. The modality matters less than the intensity.

Why Intensity Matters for Nerve Pain

When you have radiating pain — whether it is sciatica down your leg or numbness into your arm — the problem is not just at the nerve root. Over time, your central nervous system becomes sensitized. Pain signals get amplified. Things that should not hurt start to hurt. This is called central sensitization, and research shows it is present in 25–35% of patients with radiculopathy (Smart et al., Manual Therapy, 2012).

Aerobic exercise at the right intensity activates your body’s built-in pain relief system — endogenous opioids, endocannabinoids, and descending inhibitory pathways from the brainstem that dial down the sensitivity of your spinal cord (Sluka et al., Pain, 2018). Significant endorphin release kicks in around VT1 and increases substantially at higher intensities (Goldfarb & Jamurtas, Sports Medicine, 1997). An fMRI study showed that vigorous exercise produced measurable changes in pain-related brain activation — specifically increased activity in the periaqueductal gray, the brain’s primary pain inhibition center (Scheef et al., Pain, 2012).

In other words: the exercise needs to be hard enough to change your brain’s relationship with pain. A casual walk does not get there. Threshold-based training does.

How We Prescribe It

We do not guess at intensity. We use a talk test protocol to find your ventilatory thresholds — VT1 and VT2 — and prescribe from there.

High to Moderate Irritability (Pain Is Still Significant)

For patients with higher pain levels — the nerve symptoms are consistent, sleep is disrupted, daily activities are limited — we prescribe aerobic training at or slightly above VT1. This is the intensity where you can still talk but it takes effort. Inclined treadmill walking, rowing, cycling with resistance. The goal is to activate the descending pain inhibition system without flaring symptoms.

Research supports this approach. Patients with central sensitization can actually get worse with high-intensity exercise early on — their pain system is already overloaded (Nijs et al., Pain Physician, 2012). Starting at VT1 builds tolerance and progressively restores normal pain modulation over weeks of consistent training.

Low Irritability (85% Better but Stuck)

Then there are the patients who have made great progress but cannot get over the last hump. The numbness is mostly gone. The pain is manageable. But it is still there. These patients have often been doing their exercises, staying active, doing everything right — and they plateau.

This is where VT2 comes in. One to two sessions per week at or above VT2 — the intensity where conversation is no longer possible — while maintaining the VT1 base work the rest of the week. The physiological rationale: higher intensity produces substantially greater endorphin release and stronger activation of descending pain inhibition. For a nervous system that has mostly recovered but is still holding onto residual sensitivity, this can be the stimulus that pushes it over the edge.

VT1 remains the foundation. VT2 is the accelerator for patients who are ready for it.

It Is Not Just Carpal Tunnel. It Is Not Just Sciatica.

If you have numbness, tingling, or weakness in your arm or hand, it may not be carpal tunnel at all. A cervical radiculopathy — a nerve issue in your neck — produces identical symptoms. If you have shooting pain or numbness down your leg, it may not be a simple muscle problem. A lumbar disc or stenosis could be the source.

A Doctor of Physical Therapy evaluates the full picture in one visit — your spine, your nerves, your strength, your movement — and identifies the actual source. Then we build a program around it: manual therapy, nerve mobilization, strengthening, and structured aerobic training at the intensity that changes how your nervous system processes pain.

No referral needed. Call (608) 561-7733 or book online.