SUUNTO D4i - Manual (Page 31)

4.4. Apnea Timer
You can use the Apnea Timer function for interval training in freediving. To set the
Apnea Timer, follow these steps:
1.
Long press UP in the TIME mode to enter the Apnea Timer.
2. In the Apnea Timer, long press DOWN to enter settings in which you can define
the duration of the ventilation period and the incremental increase/decrease in
time for each cycle (repetition). You can adjust values with the UP and DOWN
buttons.
3. Short press SELECT, and define the number of cycles.
4. Start the first cycle by short pressing DOWN.
The timer counts down the ventilation time, which is also indicated by two short
beep tones.
5. Short press DOWN to start the Apnea cycle. Press DOWN again when a new
ventilation cycle begins. Repeat until the end of the defined number of cycles.
You can reset the apnea timer by long pressing UP.
Note that the apnea timer allows up to 20 cycles and the number of allowed cycles is
dependent on the length of the ventilation period and on the incremental increase/de-
crease. The last ventilation period cannot be shorter than 5 seconds or longer than
20 minutes.
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