Exercise substitution for injuries, $0.02 USDC on Base: give a movement (e.g

What it does

Exercise substitution for injuries, $0.02 USDC on Base: give a movement (e.g. barbell back squat) and an injury or limitation (e.g. knee pain, shoulder impingement) and get 3-5 safe alternative exercises with prescriptions, coaching cues and stop signs. Physio-informed, not medical advice. Gym, home gym, CrossFit, Hyrox.

Tags: exercise_substitution · injury_modification · fitness_coaching · bazaar

Call contract

Method

POST

Input

json

Output

json

Last paid call

2026-10-13

{
  "equipment": [
    "dumbbells",
    "box",
    "bands"
  ],
  "limitation": "patellar tendinopathy, pain in deep knee flexion",
  "movement": "Barbell Back Squat"
}

{
  "alternatives": [
    {
      "name": "Banded Spanish Squat Isometric",
      "prescription": "5 × 45 s @ RPE 6-7",
      "why": "Loads the tendon isometrically"
    },
    {
      "name": "DB Box Squat (high box)",
      "prescription": "4 × 8 @ RPE 7",
      "why": "Limits knee flexion depth"
    }
  ],
  "coaching_cues": [
    "Vertical shin",
    "Pain ≤ 3/10 during and after"
  ],
  "disclaimer": "Not medical advice.",
  "limitation": "patellar tendinopathy",
  "movement": "Barbell Back Squat",
  "stop_signs": [
    "Sharp pain below the kneecap"
  ],
  "why_avoid": "Deep knee flexion under axial load peaks patellar tendon stress."
}

Use with an agent

1. Discover. Agents find this listing with GET https://bazaar.saylorinnovations.com/discovery/search?query=…, the MCP tool search_resources, or /discovery/resources.
2. Inspect. Fetch /resources/42658.json for the price and payment options.
3. Pay. Call GET https://wod-api-production.up.railway.app/tools/substitute. The provider answers 402 with its payment requirements. An x402 client signs one of the options below and retries with PAYMENT-SIGNATURE.
4. Execute. The provider returns 200 with the data. Agent Bazaar is not in the request path and never sees your payment.

For humans

You don't need an account or an API key; you need a wallet holding a small amount of USDC on Base, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price

$0.02 / request

Protocol

x402 v2

Auth

No account or API key. Pay per request.

Networks

Base

Demand

1 calls · 1 unique payers in 30d (public x402 Bazaar data)

x402 payment requirements

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0x0395c1bed0b83ad6f0329b4132191934733e637c",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "20000",
    "amountUsd": 0.02,
    "maxTimeoutSeconds": 90
  }
]

Schemas

{
  "properties": {
    "example": {
      "type": "object"
    },
    "type": {
      "type": "string"
    }
  },
  "required": [
    "type"
  ],
  "type": "object"
}

{
  "example": {},
  "type": "string"
}

Examples

curl "https://wod-api-production.up.railway.app/tools/substitute"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

const res = await fetch("https://wod-api-production.up.railway.app/tools/substitute");
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

import httpx
res = httpx.get("https://wod-api-production.up.railway.app/tools/substitute")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header

Details

Provider

wod-api-production.up.railway.app

Endpoint

https://wod-api-production.up.railway.app/tools/substitute

Machine-readable

/resources/42658.json