Levels of Motion Control and Reaction Time – Part 1

To achieve efficient skiing, we must have certain skills in motion control. Michon (1985) proposes three capacity levels in motion control: the strategic, the tactical, and the operational.

The strategic level applies when we plan a general descent according to our criteria. This would include slope choice or off-piste agreeing to difficulty parameters, traffic, snow conditions of the chosen slope, etc. At this level, the time factor is broad.

The tactical level includes maneuverability and controlled actions, avoiding fixed and moving obstacles (other people moving), choosing direction change spots, speed, and distance for overtaking or avoiding others. This level does not include reactions in the event of dangerous situations but analyzing choices to maintain a safe descent. Here, the performing time factor is reduced to seconds.

The operational level refers to keeping our skis in a trajectory defined in advance, in which our actions would be automatic and include maintaining stable skis during motion, changing direction, weight shifting, or edging control. At this level, the execution temporal factor is reduced to milliseconds and is regulated by vision, which can be divided into longitudinal control (through central vision and optical flow), lateral control (through peripheral vision and lamellar flow), and directional control (through the focus of expansion).

Reaction Time

In skiing, the uncertainties caused by the changing environment increases the complexity of our response processing to the perceived stimuli. Our efficacy depends on our ability to react in time and space to unexpected situations. Reaction time is the interval elapsing between a stimulus or signal and our response to that stimulus. Our own skiing performance improvement will depend on our reaction time to non-anticipated situations.

Between stimulus and response, it could be milliseconds for us to react, and these stimuli may be visual or auditory. For example, a sudden skier approaching may not allow us preparing to avoid him, or the intense noise of a scraping edge on the snow could be an imminent snowboarder’s proximity warning, both situations requiring an avoiding reaction. An icy area, a rut, or a bump presents unexpected concerns if they were not visually anticipated. We must quickly react but our mental structure provides a temporal delay in the execution of that response, i.e., a reaction time.

This time varies according to our psychophysical condition, the technical level, and our experience in relation to risky situations. In certain circumstances, our ability to respond makes the difference. Sometimes we tend to react by force and/or thinking excessively delaying the response, while in others we anticipate what is going to happen, being confident that our body and our skis will go in the right direction. This attitude leads us to minimize reactions because our behavior is generally proactive, i.e., we proceed by anticipating the circumstances.

In critical self-preservation situations, we may not have sufficient time to think a suitable response as it would be a time loss, so our nervous system reacts through reflexes where our body protects itself.

According to Green (2000), reaction time decreases if the stimulus is more intense in terms of brightness, contrast, size, and volume; if central vision is employed; if there is a decent visibility; and ensures that reaction speed, in certain situations, is quicker for auditory than for visual stimuli.

While skiing we react to something we hear, see, feel, or sense and this involves a temporal interval. Mental processing time is the time we take to perceive the stimulus and to decide a response. Movement time is the time we take to execute the chosen response. According to Yerkes-Dodson law, our emotional state accelerates reaction to a possible threat but decreases fine movements execution.

External response time is the time due to external factors when we take longer to accomplish the pretended maneuvers. It is involved in motion speed, braking or turning, in skis’ friction, in snow type, and in slope inclination.

Reaction time varies in relation to our different performances and also within the same execution but with different conditions. It is a complex behavior affected by a number of variables. Reaction time plus movement time is motor response time.

The factors affecting reaction time are:

• Expectation: reaction time is reduced if we are being expectant to the possibility of having to slow down to avoid a threat or are warned by any signal as, e.g., a sign informing a trail junction.
• Novel situations induce us having to interpret them deciding the most appropriate response, which increases our reaction time.
• Emergencies: we must decide whether to stop or to turn, which takes longer to consider both options.
• Others’ behavior: we remain alert if someone slows down, turns, or falls.
• Attention: reaction time increases if our attention is not directed towards our skiing as, for instance, thinking about other things.
• Visibility: reaction time increases in terms of poor visibility conditions.
• Age: as we get older, we have longer reaction times but we compensate it by skiing in a more conservative way.
• Uncertainty: our vacillating level over a stimulus appearance affects our reaction time and if it increases, it also will reaction time.
• Experience: exercising tends to improve speed and reaction precision due to visual and motor anticipation.
• Muscle tension: for an efficient reaction, our muscle tension level should be functional; not too relaxed neither too tense.
• Vision: if we detect a stimulus by our central vision, we will produce a quicker reaction than if it is done by our peripheral vision.
• Fatigue: muscular and mental fatigue increase reaction time.
• Physical condition: a good physical shape allows us quicker reactions.
• Corporal dominance: in most cases, we make use of our dominant side to stop or turn in an emergency.
• Speed: motion speed intervenes directly in reaction capacity since higher speeds cause longer reaction times.
• Complexity: more complex responses cause slower reaction time.
• Stimulus intensity: we tend to react quickly to something louder, brighter, or with greater contrast.
• Second activity: paying attention to a second activity as listening to music or filming may affect, in some situations, our visual perception and hearing function limiting skiing attention since they create a constant distraction.

Generally, these factors tend to alter our behavior by paying less attention to slope conditions and to other people. In addition, they would disrupt cognitive processes in object identification and action possibilities, increasing our reaction time.

Neuroscientific Framework Matrix for Motion Control and Reaction Time

Concept / Control Level	Temporal Window	Primary Sensory & Visual Inputs	Neural & Cognitive Mechanism	Behavioral Reaction	Skiing Scenario / Trigger	Skiing Outcome & Mechanical Efficiency
Strategic Level	Broad / Unrestricted	Macro-environ-mental scanning (Vision)	High-level executive function, conscious planning, and risk calculation.	Deliberate path planning and choosing parameters before descending.	Selecting an off-piste run or a specific slope based on difficulty.	Macro-efficiency; optimal line choice matching ability to snow traffic.
Tactical Level	Reduced (Seconds)	Middle-range spatial vision and auditory tracking	Cognitive evaluation of alternative actions; proactive hazard avoidance.	Safe maneu-vering, proactive speed adjustments, and gap manage-ment.	Overtaking a slower skier or choosing a spot to initiate a turn.	Sustained safety margin; dynamic rhythm maintenance without emergency braking.
Operational Level	Ultra-fast (Milli-seconds)	Tri-directional vision: central, peripheral, focus of expansion	Automatic motor schema execution; subcortical control loops.	Continuous balance maintenance, weight shifting, and edge angle modulation.	Stabilizing skis automatically while hitting an unexpected rut or bump.	High micro-efficiency; instan-taneous tracking and trajectory preservation.
Longi-tudinal Control	Milliseconds	Central vision and Optical flow	Foveal stream processing tracking forward movement vectors.	Incremental modi-fications to forward velocity and deceleration.	Assessing acceleration on a steep pitch while facing downward.	Precise speed control along the longitudinal axis of the ski trail.
Lateral Control	Milliseconds	Peripheral vision and Lamellar flow	Extrafoveal stream processing tracking side-to-side environ-mental shifting.	Real-time lateral balance corrections and adjustment of stance width.	Maintaining a safe distance from trees or skiers on the margins.	Flawless lateral spacing; minimi-zation of side-to-side instability.
Directional Control	Milliseconds	Focus of expansion	Optic flow centering and point-of-heading calculation.	Micro-steering adjustments toward the chosen visual destination point.	Guiding skis cleanly through a narrow opening between two moguls.	Exact trajectory execution along the intended physical path.
Mental Processing Time	Varied (Milli-seconds)	Auditory, Visual, and Somato-sensory	Sensory transduction, feature binding, and cognitive motor selection.	Identifi-cation of an unexpected hazard and deciding how to move.	Hearing a scraping edge behind and recognizing an approaching snow-boarder.	Determines the systemic delay before any physical movement begins.
Movement Time	Milliseconds	Proprio-ceptive feedback	Efferent motor command delivery and skeletal muscle contraction.	Physical execution of the chosen turn, slide, or braking stance.	Physically dropping hips and driving feet laterally to bite ski edges.	Dictates the physical speed and force application of the maneuver.
External Response Time	Physics-dependent	Tactile snow feel	Frictional and gravitational interaction between ski and snow.	Skis sliding, carving, or skidding against the underlying snow pack.	Skis sliding across a sheet of blue ice versus sinking into heavy slush.	Dictates the terminal braking distance and turning radius achieved.
Reflex Reaction	Instanta-neous (Sub-millisecond)	Sudden intense threat inputs	Subcortical or spinal mono-synaptic sensory-motor reflex loop.	Involuntary, automatic, protective physical muscle contractions.	Catching a sudden downhill edge or getting snow sprayed in the eyes.	Immediate self-preser-vation; instanta-neous balance or eye protection.
Proactive Behavior / Antici-pation	Negative delay (Pre-emptive)	Visual and motor memory forecasting	Feedforward neural mechanisms; predictive motor program-ming.	Minimi-zation of sudden reactions through early, fluid positioning.	Spotting an icy patch early and turning before reaching it.	Maximum efficiency; smooth skiing with minimal abrupt corrections.
Arousal / Threat Response	Milliseconds	Sudden close-range visual/auditory threats	Sympathetic nervous system surge; emotional state acceleration.	Rapid, forceful muscle engagement optimized for heavy bracing.	A skier suddenly cutting off in front at high speed.	Accelerates raw survival reactions but degrades fine motor control.
Stimulus Intensity Modulation	Milliseconds	High-contrast, bright, or loud inputs	Accelerated sensory gating and rapid cortical registration.	Faster initialization of the mental processing phase.	Spotting a highly visible, bright neon trail junction sign.	Shortened overall reaction time due to quicker initial perception.
Attentional Distraction	Elongated (Delayed)	Dual-task sensory inputs (e.g., audio head-phones)	Cognitive bottlenecks; competitive inhibition of attention networks.	Delayed sensory detection and sluggish hazard identifi-cation.	Listening to music or filming with a camera while moving down a slope.	High collision risk; failure to perceive and identify hazards in time.