Preferred and energetically optimal transition speeds during backward human locomotion

Area of Science:

• Biomechanics
• Human locomotion

Background:

• Backward locomotion shares similarities and differences with forward locomotion.
• The backward preferred transition speed (BPTS) has not been compared to the energetically optimal transition speed (EOTS) or forward preferred transition speed (PTS).

Purpose of the Study:

• To determine if BPTS aligns with EOTS.
• To investigate the relationship between backward and forward preferred gait transition speeds.

Main Methods:

• 12 healthy young adults participated.
• Subjects familiarized with forward and backward treadmill locomotion.
• Measured VO2 and RPE at various speeds around BPTS for walking and running backward.
• Calculated EOTS from energy-speed curves and compared it to BPTS.

Main Results:

• EOTS (1.85 m·s⁻¹) was significantly higher than BPTS (1.63 m·s⁻¹).
• Rate of Perceived Exertion (RPE) was similar for walking and running at BPTS, but oxygen consumption (VO2) was higher when running.
• A strong correlation (r=0.82) was found between BPTS and PTS.

Conclusions:

• BPTS is not the same as EOTS, indicating factors beyond metabolic energy influence backward gait transitions.
• Backward gait transitions share similarities with forward locomotion.
• Preferred transition speeds for backward and forward locomotion are strongly correlated.