7.4 Cycle Testing, Validity, and Termination Criteria

5. Submaximal Cycle Ergometer Protocols: YMCA Multi-Stage Test

The YMCA Submaximal Cycle Ergometer Test is a standardized, multi-stage branching submaximal test performed on a mechanically braked cycle ergometer (e.g., Monark ergometer). It is designed to establish a linear relationship across two distinct submaximal workloads to extrapolate predicted $VO_{2max}$.

+---------------------------------------------------------------------------------------------------+
|                         YMCA SUBMAXIMAL CYCLE ERGOMETER BRANCHING ALGORITHM                       |
|                                                                                                   |
|                                      [ STAGE 1: ALL CLIENTS ]                                     |
|                                  Pedal Rate: 50 rpm (Constant)                                    |
|                                Resistance: 0.5 kg (150 kgm/min / 25W)                             |
|                                Duration: 3 minutes (Record Min 2 & 3 HR)                          |
|                                                |                                                  |
|                 +------------------------------+------------------------------+                    |
|                 |                              |                              |                    |
|          HR < 80 bpm                   HR 80 - 89 bpm                 HR 90 - 100 bpm      HR >100 |
|                 |                              |                              |               |    |
|                 v                              v                              v               v    |
|           [ STAGE 2 ]                    [ STAGE 2 ]                    [ STAGE 2 ]      [STAGE 2] |
|         2.5 kg (750 kgm)               2.0 kg (600 kgm)               1.5 kg (450 kgm) 1.0kg(300)  |
|                 |                              |                              |               |    |
|                 v                              v                              v               v    |
|           [ STAGE 3 ]                    [ STAGE 3 ]                    [ STAGE 3 ]      [STAGE 3] |
|         3.0 kg (900 kgm)               2.5 kg (750 kgm)               2.0 kg (600 kgm) 1.5kg(450)  |
|                 |                              |                              |               |    |
|                 v                              v                              v               v    |
|           [ STAGE 4 ]                    [ STAGE 4 ]                    [ STAGE 4 ]      [STAGE 4] |
|        3.5 kg (1050 kgm)              3.0 kg (900 kgm)               2.5 kg (750 kgm)  2.0kg(600)  |
+---------------------------------------------------------------------------------------------------+

Step-by-Step YMCA Cycle Ergometer Protocol

1. Pre-Test Setup: Adjust seat height so that the client's knee exhibits $5^\circ$ to $10^\circ$ of flexion at bottom dead center when the ball of the foot is on the pedal (pelvis level, no rocking). Set metronome to $100\ \text{bpm}$ (each click represents a single downstroke, yielding a constant pedal cadence of $50\ \text{rpm}$).
2. Stage 1 Baseline: All clients begin Stage 1 at an initial workload of $150\ \text{kgm/min}$ (0.5 kg resistance at 50 rpm; 25 Watts) for 3 minutes. Record heart rate during the final 15 to 30 seconds of minute 2 and minute 3 to confirm steady state ($\le 5\ \text{bpm}$ difference). If not steady, extend stage by 1 minute.
3. Branching Workload Selection: The steady-state heart rate achieved at the end of Stage 1 dictates the resistance for all subsequent 3-minute stages (see branching diagram above):
   • $\text{HR } < 80\ \text{bpm} \rightarrow \text{Set Stage 2 to } 2.5\ \text{kg } (750\ \text{kgm/min})$.
   • $\text{HR } 80\text{--}89\ \text{bpm} \rightarrow \text{Set Stage 2 to } 2.0\ \text{kg } (600\ \text{kgm/min})$.
   • $\text{HR } 90\text{--}100\ \text{bpm} \rightarrow \text{Set Stage 2 to } 1.5\ \text{kg } (450\ \text{kgm/min})$.
   • $\text{HR } > 100\ \text{bpm} \rightarrow \text{Set Stage 2 to } 1.0\ \text{kg } (300\ \text{kgm/min})$.
4. Test Termination Criteria: The test continues through progressive stages until the client achieves two consecutive stages with steady-state heart rates between $110\ \text{bpm}$ and $85\%$ of age-predicted maximum heart rate ($0.85 \times [220 - \text{Age}]$). Heart rates $<110\ \text{bpm}$ are excluded from extrapolation because stroke volume has not yet plateaued, confounding the linear relationship.
5. Extrapolation to $VO_{2max}$: The two steady-state HR data points are plotted against their corresponding workloads. A linear regression line is extended to the client's predicted $\text{HRmax}$, dropping a vertical line to identify predicted maximal workload ($W_{max}$ in kgm/min). $VO_{2max}$ is then calculated using the ACSM cycling metabolic formula:

Astrand-Rhyming Submaximal Cycle Ergometer Test

Unlike the multi-stage YMCA protocol, the Astrand-Rhyming Test is a single-stage 6-minute submaximal test. The client pedals at $50\ \text{rpm}$ at a constant workload (typically $300\text{--}600\ \text{kgm/min}$ for unconditioned females, $600\text{--}900\ \text{kgm/min}$ for conditioned males) designed to elicit a steady-state heart rate between $130$ and $170\ \text{bpm}$ between minutes 5 and 6. The steady-state HR and workload are plotted on the Astrand nomogram and multiplied by an age-correction factor (since the nomogram was originally derived from 25-year-old subjects).

6. Indications for Immediate Cardiorespiratory Test Termination

Personal trainers must continuously monitor the client's subjective appearance, facial coloration, breathing effort, heart rate, and hemodynamic metrics (blood pressure). The trainer must immediately terminate any submaximal or maximal cardiorespiratory test upon observing any of the following clinical or physiological red flags:

+---------------------------------------------------------------------------------------------------+
|                         CARDIORESPIRATORY TEST TERMINATION CRITERIA                               |
|                                                                                                   |
|   1. VOLITIONAL REQUEST       --> Client requests to stop, verbalizes severe distress, or          |
|                                   exhibits physical manifestations of extreme exhaustion.         |
|   2. HYPOTENSIVE RESPONSE     --> Drop in Systolic Blood Pressure (SBP) > 10 mmHg from baseline   |
|                                   despite an increase in workload, with other evidence of ischemia|
|   3. HYPERTENSIVE CRISIS      --> Excessive blood pressure rise: SBP > 250 mmHg and/or             |
|                                   Diastolic Blood Pressure (DBP) > 115 mmHg.                      |
|   4. SIGNS OF HYPOPERFUSION   --> Lightheadedness, confusion, ataxia (stumbling gait), pallor      |
|                                   (pale face), cyanosis (blue lips/skin), cold/clammy skin.       |
|   5. ANGINAL SYMPTOMS         --> Onset of angina-like discomfort (chest pressure, pain radiating |
|                                   to left arm, neck, jaw, or upper back).                         |
|   6. BLUNTED CHRONOTROPIC     --> Failure of heart rate to increase with increasing exercise      |
|      RESPONSE                     intensity (chronotropic incompetence).                          |
|   7. SEVERE DYSPNEA / CLAUD.  --> Severe shortness of breath, wheezing, or severe leg claudication|
|   8. EQUIPMENT MALFUNCTION    --> Failure of cycle brakes, heart rate monitor, or sphygmomanometer|
+---------------------------------------------------------------------------------------------------+