A selection of tested blends for sore and aching muscles:
Blend one: 3 drops each Basil linalol and Black Pepper, with 2 drops Ginger essential oil is a 2.5% dilution. This could be used for a full body massage for adults,or to "spot treat" problem areas.
Blend two: 4 drops Lavender Population, 4 drops Eucalyptus smithii, and 3 drops Ginger. This is a 3.75% dilution. A bit stronger than the above. I have found this blend wonderful for the aches and pains of the flu, or the pain in the diaphragm caused by excessive coughing. It is also a wonderful bath blend.
Blend three: 2 drops Black Pepper, 4 drops Helichrysum italicuum (Balkan), 6 drops Lavandin Super. This is a 4% dilution, not really appropriate for full body massage but wonderful just to rub in "where it hurts." This is also a soothing blend for nerve and joint pain.
Another blend, that I have found useful for muscle spasms (which tend to wake me in the middle of the night!) to 1/2 fl ounce of Arnica Infused oil add 6 drops Helichrysum italicuum and 6 drops Kunzea. For me, this blend has been very effective.
All of these blends are even more effective when either St. John's Wort Infused oil or Arnica infused oil is used for at least part of the massage base.