SELECT
   WEEKOFYEAR(recording_datetime) AS week,
   team_skey,
   avg(heart_avarage) AS heart_avg
FROM
   ajax
WHERE
   team_skey = '1' or team_skey = '8'
GROUP BY
   WEEKOFYEAR(recording_datetime),
   team_skey
ORDER BY
   week ASC, team_skey ASC