def oxygen_cost_v(v):
  """Effectively defines Daniels' pace-power relationship.
  
  AKA speed-to-vdot.

  Assumed to be the same for all runners.

  Args:
    v (float): velocity in m/min.
  Returns:
    float: oxygen cost to cover distance in mL/kg/min.
  """
  a1 = 0.182258
  a2 = 0.000104
  c = -4.60

  return a1 * v + a2 * v ** 2 + c