Dehydration: feeling unwell, dark color or strong smelling urine, low energy during training, high resting heart rate, constipation, lower VO2 max, thirst, chapped lips, muscle cramps

Low Carbohydrate Diet: poor sleep, sugar cravings, irritability, feeling flat during training, not recovering after a workout, general fatigue, frequent infections/illness

Hypoglycemia: sugar craving, nausea, irritable, foggy, lack of concentration, shakiness, aggression and headaches

Low Protein Diet: frequent infections, low energy, sleepy, susceptible to injury, poor recovery

Hemolysis: dark stools

Anemia: low blood hemoglobin and hematocrit*, fatigue, poor sleep, low energy during training, weakness, loss of appetite, pallor, constipation, depression

*assuming no volume expansion from training

Iron Depletion: unlike anemia, iron stores are low but not gone with normal hemoglobin level, low energy, heavy legs, fatigue, low motivation, low VO2 Max, lower lactate threshold

Stress Imbalance: insomnia, diarrhea, upset stomach, high heart rate, fatigue, muscle tightness, irritability, menstrual abnormalities, frequent infection

Over-training, Over-reaching, Under-recovery: not responding to training, poor performance, tiredness, fatigue, staleness, poor sleep, high resting/morning heart rate, suppressed heart rate at high intensity exercise, apathy, frequent infections, restlessness, persistent muscle soreness

Heat Exhaustion: headache, vertigo, fatigue, nausea, flushing, increased heart rate, disorientation, weakness, anxiety

Hypothermia: disorientation, lethargy, clumsiness, confusion, irritability, extreme-slowed respiration or heartbeat

Checking your resting heart rate in the morning is good practice to catch early signs of over-training/reaching, poor diet, infections and many of the above symptoms. Elevated resting heart rate usually is a good indicator to check for one of the above signs which will lead to training downtime and/or poor performance in races.

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