Do it now task!

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Across
  1. 2. Swedish type of training
  2. 5. exercise without oxygen
  3. 6. several activities with a short rest inbetween
  4. 8. professional athletes work on keeping this quite high
Down
  1. 1. high intensity training with short breaks
  2. 3. exercise with oxygen
  3. 4. activity without rest
  4. 7. blood heart and blood vessels