Join same table twice in SQLALCHEMY selecting only some columns

Question

Consider I have 2 models:

class User(db.Model):
    __tablename__ = 'user'
    id = db.Column(db.Integer, primary_key=True)
    email = db.Column(db.String(255), unique=True)

class Activity(db.Model):
    __tablename__ = 'activity'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
    tech_id = db.Column(db.Integer, db.ForeignKey('user.id'))

I would like to perform a query that gives me as result all activities with for each one: name, user email, tech email

db.session.query... ?